To MHG

You say that speedrunning is antisocial. I disagree. Between Twitter, IRC, Discord, Mumble, forums, stream chat, and other things, we’re constantly talking to each other. True recluses and lone wolves (ssbmstuff, Grav) are pretty rare, and even those two examples are well-respected in speedrunning because they spend an absurd amount of time playing their games instead of talking to people.
There are DEFINITELY consequences for your social behavior during speedrunning. I (PvtCb) and Cyberdemon531 are nearly textbook examples. We have no filters and we act like idiots and try our best to discredit actual idiots, and because of that there are a decent number people who dislike us. GDQ staff disliked us (partly for things we actually said, partly for things they thought we said), and because of that they were itching to ban us from their events.
Learning a speedrun can be hard, but there are usually 2 way of going about it. You either are learning a popular game, in which case resources and runners are abundant. The other option is learning a niche game, in which case you’re usually on your own unless you get a runner to help you. Either way, you’re probably going to need human interaction. Complaining about this is like complaining that your art teacher isn’t a robot. Speedrunning is a mix of hard science and art/creativity, and while the hard science part can be learned independently, the second part needs some form of tutor (or at least experience to develop).
Loss of leadership is NOT an issue; if anything, the community has gotten much better since their decline. Their major contribution was getting speedrunning popular, which has been a double-edged sword. I’d argue that a lot of the current issues from speedrunning stem from the fact that it was concentrated so heavily on so few individuals for a long time.
Games Done Quick has a lot of issues, but I’d say that their issues are much more related to exploitation of runners and being the gatekeepers to popularity. “Cringe” is not an issue.

In short, speedrunning is in a fucked place, but not from what you described. It’s because there’s a dichotomy between the grassroots players creating content and doing runs and the large runners who want to be what Cosmo and Siglemic used to be and let GDQ try to turn the whole thing corporate and line their pockets. These two sides are going to have to come to a compromise soon or their will be consequences.