I agree with Stan - this is nothing new. It long predates this forum, or even Rick himself. While the acronym FOMO (fear of missing out) may be new, the concept is not. And as Rick is always saying, "Americans get the second-shortest vacations in the rich world," so there's great pressure to see as much as possible in as short a time as possible.
I also agree that it's chicken and egg. Due to the above factors, escorted package tours try to cram in as much as possible (even Rick's, although to a lesser extent). People read about these tours, and in turn think they not only can duplicate that on their own, but that they should. So, demand and desire are driving busy itineraries, and busy itineraries are driving demand/desire for them.
When I come upon one of these threads, I look at a few things before responding. Do they truly seem to be asking for help, or are they just asking for validation? (There is a difference between lack of knowledge, and lack of willingness to acquire knowledge). And how have they responded to good suggestions - with hostility, or with receptiveness? If they seem genuinely open to making changes, I may contribute (if I'm not duplicating other responses too much). If they aren't, I just ignore the thread - better for my blood pressure!
Finally, I agree that lots of these issues are "first time traveler" issues, which is why I try not to be judgmental (not always successfully). However, we do get some threads from people who have explicitly stated that they have done very busy itineraries in the past and loved them, and are looking to duplicate this on their next trip. I avoid these threads, because I can be of little help for someone who says they saw all they needed to see in Paris or London in two days.