"You all can check the leaderboard—even Legendary Grandmasters are unable to solve Problem F, and Grandmasters and Masters are struggling with E1 and E2. Why waste such hard-made problems on a Division 2 contest instead of saving them for Division 1? What's the point of putting questions that are unsolvable by Division 2 participants? Contest difficulty should increase linearly, but it often spikes abruptly. What do you all think about this? Feel free to criticize, correct, and share your opinion."
In top 500 only two F solutions, rainboy and saptarshi8103... In top 500 only one E2 solution, rainboy...
Giving Hard problem to Upsolve
I think the actual issue is not problem difficulty, but that contests are too short for anyone to try E/F unless they have GM tier speed. But I agree it's silly to add them if no one reaches that point, I would prefer 3 hour contests personally.
I would prefer 20 minute contest, because I would get 2200 perf every time...
There aren't a lot of Div 1, so I guess putting challenging problems in Div 2 keeps Div 1 users busy. Also, it happens that difficulty isn't well estimated by authors, but we can't really blame them for that.