The big things I wanted to hit on why has the traditional adventure/game seemed to have been replaced?
I think that it hasn't really been replaced. It no longer being quite so dominant is not the same as replacement.
Why the weird weird mixed feelings on Thirdparty/homebrew content?
Because third party and homebrew content is of mixed quality.
Why is the current online recruiting spots (reddit, Startplaying) so... bad?
Because RPG play is high on interpersonal interaction, but online recruiting doesn't give you a great idea of what people are actually like.
Why are modern players so bad at the game and the seeming want to remove the G from RPG?
Why are there people who want to go out to get Indian food instead of pizza?
Different people just want different things, dude.
I grew up reading Dragonlance, Dragon riders of Pern and a bunch of fantasy. I grew up watching a bunch of shows like the DnD cartoon, Pirates of Blackwater, Masters of the Universe and more
Which means you grew up on things that were largely off the air or otherwise had their heyday years before you were even born.
Entertainments change with the times they are in, and shift to meet the realities of their audiences. So, modern games aren't likely to focus on the styles of decades past.
So many games I see posted are more or less giving away the whole plot like reading the back of a book. The art of subtly is lost...
I don't know that the media you referenced was really known for its subtlety, either.
When you're posting games for a wide audience, you have a choice:
1) Tell folks what they are getting into, so they can make informed choices
2) Leave them in ignorance, and hope they are into what you're laying down just by random chance.
Leaving it up to chance is a good way to have people all around disappointed.
and seems very much like the DM has a story they want to tell, if your lucky your characters will have their backstory factor in.
You yourself just mentioned that online methods of meeting gamers kinda stink. In general, loads of folks report that finding groups to play with is as best haphazard.
Building bespoke campaigns for players who you aren't sure are going to make it to more than a couple sessions, or match your playstyle, or even be people you want to hang around with frequently, isn't a winning proposition for the GM.
So, the GM builds something they like themselves, or buys some published adventure content, and runs it - you like it, or you don't.