Me and my wife talk about this a lot. Older people didn't have to come up in a world where facts are malleable and truth is blatantly manipulated. The idea of a "good source" has literally never occurred to our parents. They see a post on Facebook and assume it's true without researching the biases of the authors. It's a little scary, to be honest, because I'd bet 80% of older folks are like that. (And the ones posting on this forum likely aren't, because you're way more tech savvy just to be on a forum like this than your peers, so don't take it personally boomers).
The whole "millennial whining" thing is more about pointing out the trends and the material facts for many youngish Americans compared to the previous generations. It's not really whining to point out that boomers came up during one of the most prosperous times in history, but that this country has significantly changed since the 1980s, making it much more difficult for many youngish Americans to achieve the same level of stability and prosperity that their parents were gifted with.
But yes, muh bootstraps.