I guess it depends exactly what you mean by “social media.”
If you mean the general ability for people to communicate over the internet with each other in a public way: No. It is unequivocally good for people to have more access to information and be able to communicate freely with people around the world. These kinds of developments in communication and information distribution technology have always lead to big, usually positive social changes. The prime example of this is the printing press. By greatly lowering the cost of mass producing books, it allowed more people to become literate and rather than relying on the church or other authorities handing down knowledge to them, they were able to read directly from the source as well as produce their own works. This can be considered a heavily contributing factor to the social movements that followed over the next few centuries, The protestant reformation, the enlightenment and the revolutions against feudalism that it inspired, etc.
Did people print books with misinformation? Yeah. Did governments print books which tried to reinforce their rule? Of course. Does that mean books were a mistake? You would have a really hard time convincing me that they were.
Similarly, social media has allowed us to get our information and talk to each other free of the old gatekeepers. Corporate news media used to be the only way to know what was going on in the rest of the world. They chose what to cover and how to frame that coverage. While you could learn some things from it, what they omit is often more important than what they report. Before liberating the camps, most Americans had no idea of the full extent of the horrors perpetrated by the Nazis. Today, we see the cold hard reality of the genocide going on in Gaza and that has done much to shift people’s opinions on it and start to take more action.
Before social media, your ability to talk to people was pretty much limited by who was immediately around you or who you knew the phone number of. It’s hard to organize people like that. It’s hard to empathize with people far away who you’ve never met. The gov can easily stoke xenophobia because they were entirely in control of the way people perceived and interacted with that population. They could convince people that those people in some other country are all crazy people who hate us and hate freedom and wish to destroy us even to their own detriment. With social media, you can just talk to a lot of these people directly. You see that despite some cultural differences, they’re normal ass people like us who go about their lives just like us and want the same things as us. They watch the same movies as us. They play the same games as us and even play with us sometimes. It’s a lot harder to hate someone once you know them like that.
But now we reach the crux of the issue which is specifically talking about corporate social media. The profit incentive always leads to decisions which compromise the very purpose of the thing. Algorithms are a borderline necessity to manage the unfathomable amount of information uploaded to the internet every minute. However, personalized advertising and the mass surveillance that it requires can chill speech, warp what kinds of discussions and content go on these platforms, and corrupt search results and algorithmic recommendations. They can show things that are beneficial to advertisers, they can optimize around engagement to get people to spend more time scrolling through ads, creating addictions, they can optimize around negativity because people respond to that more than positive or neutral things, etc.
And that’s just the pure capitalist logic side of this. Obviously governments and other interest groups see the power of social media to shape perception of the world and they are terrified of losing their monopoly on “truth.” So they make use of it themselves or worse: They collaborate with the tech companies to mooch off their mass surveillance or tweak algorithms to guide conversations.
This unholy nexus of capitalist interests and government surveillance and propaganda IS a problem. I’m not entirely sure I would call it a “mistake” though. Most of these sites didn’t start out this way. They did the anti-competitive thing where they started out offering a good service at a low price (usually free) and as they gained a dominant market share, they slowly shifted to less user friendly policies. That plus the network effect made concentrating internet activity on these handful of sites less of a decision and more of an inevitability. What we do from here likely requires regulation. As much as I like the fediverse, it seems very unlikely that people will move en masse to networks that barely have any people or content. Of course such regulation can’t really be expected to solve the problems while our governments are controlled by capitalists. So there’s a bit of a chicken and egg problem.
But I think despite all of that, they trend is broadly moving in the right direction. It might not seem like that if you look at our governments and corporations, but fascism is ultimately a reaction to the threat of popular will taking away the ruling class’s power and privilege. The very fact that we are seeing this backlash from the top means IT’S WORKING. We are getting closer to class consciousness. Like I said previously, humans have a negativity bias, so it can be easy to focus on the bad participants of the internet. However, the thing to keep in mind is that a lot of that is bots/astroturfing or people being duped by them and that algorithms focus on negative news and interactions to boost engagement, all of which create a warped sense of scale for how much of the internet is reactionary.
You need to understand all of that if you want to effectively utilize social media for all of the benefits it can provide.
It’s very debatable, but I also think it’s not that relevant. The world doesn’t exist in a static, idealized form for all eternity. Things change over time through their interactions with other things. That’s at the core of dialectical materialism. It can be useful to analyze the past and how particular forms of social and economic arrangements influenced the development of human societies, but I don’t think it really says much about what we should be doing now. We don’t have the counterexample of a world that developed differently. All we can say is what happened. The world developed that way, for all the good and bad that came with it. But we don’t live in a world where most people are illiterate hunter gatherers or peasant farmers anymore. We need to analyze the reality we exist in as it is now without presuming that this represents some natural state.