But the independent sites are dying for a reason

Because you'll try to put something up and you get flooded with spam/hacking attempts and whatnot

Because registering a domain, deploying wp, etc if not so trivial

Gmail and other "big email providers" are needed since there's no litigation against email abusers, and there's a constant flood of crap to the spam folder

Walled gardens are surely problematic but they're less trouble than going independent.