YouTube's poor bitrate is to thank for that, a lot of channels put up 60fps videos even of 30fps content to get better quality out of it. The videos are still showing 30fps. So if just seeing the "60fps" by the yt indicator made people more excited for game even though they were looking at 30fps stuff, folks need to reevaluate just how much 60fps actually matters to them.
I wonder though if youtube interpolates to 60FPS when a 30FPS video is uploaded as 60FPS there but I guess not. -Though there are some videos interpolating Breath of the Wild to 60FPS and it looks amazing, most of them are filmed from the TV that is doing the interpolation though and I wouldn't want to play myself with such have post processing enabled, the input lag mus be like hell...
The reason is double the frames.
Some folks don't even like to settle for 60 frames anymore, there's a reason I bought a 144hz monitor.
I think 60 is good enough for almost everything, sure more is always better but you'll need the monitor for it, like you have. The difference between 30 and 60 is just huge, between 60 and 120 it's still noticeable but not that much.