Would you guys switch to another platform if you weren't so invested into Steam?

If I started with 0 games and was choosing my platform, I'd be torn between GOG and Steam, but would still choose Steam because of Steam Input, Broadcasting and all those other cool features.

No, because Steam is the only platform with assets, p2p trading and a community market.

People very often forget that steam is not just another store. It's a platform. Steam provides a lot of very cool (from both game developer and a gamer perspective) features and APIs like steam input, steam vr, steam matchmaking, steam workshop, steam cloud, steam anticheat, etc. So no, I wouldn't switch to another platform, because there is no platform (yet) as feature rich as steam is.

Yep! The only thing really tying me to Steam is the cloudsave feature and automatic updates. If other platforms were offering that (especially Itch) I'd be happy to switch over, provided they had an app that's otherwise just as good.

No .. why do you need to chose one ? .. you can use all of them :P
Buy chosing to use a single platform just because you invest to much in it .. is just stupid .. and thant means that the only meaning of use of that platfrom is to "brag" about your investment and the fact that you don't have the balls / money to start from 0 again ;)
In the end you should focus playing the games you like no mather what platfrom you use
PS: sry for my bad english

I would not. Why? Because Steam has decent amount of good features that other shops don't, and even those that share certain features steam tends to be better at them.

Another important reason is because steam has a huge choice of games. Sure things got out of hand once they shut down greenlight, but I'd rather use platform that has huge selection of games than one that has limited selection. I have a good deal of awesome indie games on steam that can't be bought elsewhere.

The existence of bundle sites where you can get good deal of games for cheap also benefits steam a lot.

While steam definitely has things where it should improve, and features that should be added it remains the best platform compared to the rest regardless.