Couple of my own observations:
Facebook is accessible and ubiquitous, no extra step is required to use the groups. Yes, the information is kind of poop but for 80%+ of people, they can't tell if they are getting it from an expert or an idiot. It is less about knowing everything but more about knowing when you don't know, then learning who to ask, and figuring out if that is good information. (This is also a key aspect of our current political/news situation) I ask y'all for help because I know my limitations. I can assume that if you have never been exposed to forums/BBs/message boards you wouldn't think to look there. If you did look for a forum lots of the content is obstructed by a login/registration wall which can turn lazy people away.
I started using forums in 2004ish and adore them because you get the absolute specialists input on whatever the subject is. I wouldn't ask the general public about a specific part number but if I ask Y'all what the thread size and id of a Blowsion scupper for a superjet is, one of you will know. Hell,
@JetManiac is an encyclopedia on almost any part.
The permanence of a forum is amazing (except for when photobucket photo-phuck'dit up for everyone). Being able to search (when the search function works) for content that dates back decades is incredible and also has shown how users and communities have changed. I have not used facebook in 8+ years so I am not sure if it is still the case but I remember when the feed "by time" feature was removed and content started being displayed by other algorithms. If you stick around long enough, you start to leave a mark and get to help give back to the place that helped you.
Lots of this is not nearly as generational as everyone thinks. (Disclosure: I was born in 1990) I have to help my dad (born 1959) keep from blowing stuff up more than I do my friends. Part of that is that he is not interested in this stuff, he wants to have a toy that he can put gas in, enjoy it, and ignore the not fun maintenance part of it. My friends and I (and you degenerates) are interested in modifying, ridding the crap out of stuff, and maintaining it so you can keep enjoying it. Additionally, it is really hard to be good at something you aren't interested in.
One major thing that the internet and social media has done that has major repercussions for our mechanical hobbies is giving idiots an easy platform to "show off" their work and "skills" I really feel like this normalizes a lot of bad habits and sketchy practices. That being said not everyone is an expert so we can't expect perfection all the time, especially when people are learning. I am just blown away when I see blatantly bad/dangerous stuff get praised. If I do something wrong or dangerous, I want it pointed out, that is how you improve.
Someone who thinks that they are an expert in something will be vocal about it even if they know only a little bit. (I am/was guilty of this but age and self reflection is helping me be better about it)
Leave the world a better place than you found it.
Sean