And certainly dealing with people online can result in unpleasant interactions. I found that specialized forums were usually well managed and wouldn't tolerate abusive members, though new members were expected to learn the forum's rules and put some effort into finding existing info before they start asking questions. The downside of AI is that it can only tell you things that are already visible online, and it will take the stance of the majority. On a forum you would get people who can chime in based on their experiences where there's absolutely no prior info online, or people who could contest the majority and explain why.
Synthetic data certainly could solve this. Especially if we get AI controlled robots or AI managed physically accurate simulations of the world, such that AI can actually engage with the world and test new things. It will take a long time before we get to that point where AI is able to reach the level of being able to tell you something like "oh yeah if you take apart that DSLR lens, the screws holding the floating group in place are glued in with loctite. And for good reason, if you don't have an optical bench you're never going to be able to get those elements recalibrated if you adjust them. But it looks like your copy has a shim behind that group - try removing that and see if that lets you focus past infinity." Like AI can understand a lot of that in the abstract, and might be able to guess at some of it, but until it's actually pulled apart this lens and messed around with it it's going to be vulnerable to just making things up or simply not knowing key details. But that's why it does so well with code, since all code is accessible to it.
I do agree that AI is useful though, and I have no qualms about using it to learn things faster, build tools that help me, or do my job. And though AI has contributed to the loss of the internet I value, it's not the only contributor, and likely not even the main contributor. Search engines were already consolidating power into a smaller subset of large commercial sites rather than surfacing forums and blogs, sites naturally went offline over time and archiving efforts just weren't sufficient to make up for this, and users just prefer lower effort forms of engagement like scrolling Reddit with everything in one place and lots of entertainment rather than being a member of multiple more focused communities. So while I may malign AI for the impact it has had, you're probably right that on this topic the net impact is positive.