Yeah definitely, wanting to complete every game 100% is a bit much. I’ll only ever do the side content that I actually enjoy. Ratchet and Clank: RA was great for this as it was easy and fun to complete everything (hence it being the only game I’ve managed to get all the trophies for).
In terms of keeping my to-play list short, I’ve done a pretty good job of not buying any games in Steam sales recently. Because 99% of the time they’ll be on sale again in the near future - buying them now only causes paralysis like you say.