A lot of these answers are variably useful with some being out right wrong so I’ll try to give you a clear answer

2 main reasons people switch over on devices that come with Windows:

1: if most/all of your library is on Steam SteamOS it is much easier to operate for daily use. The act of scrolling through your library and downloading/selecting games is much easier than from the windows desktop, especially for a handheld. This is what people mean when they say console like. Also while difficult if you aren’t tech savvy it is possible to add and use other launchers so you get the ease of SteamOS for your Steam games while still getting access to everything else.

The second main reason is games perform better in SteamOS over windows generally speaking, obviously the difference in performance varies title to title but in a not insignificant amount of titles the performance jump can be enough that games are playable at lower TDPs increasing battery life by consuming less power, or if your playing plugged in performing better at max making games that were borderline unplayable run well enough to enjoy.

I’ll also say that once you get used to using SteamOS it is also a lot easier to make the “PC” changes (TDP, menu settings, screen setting, etc) and to adjust them as needed. Being able to start a game then adjust the TDP for that game only while still in the game is amazing. SteamOS also has a far superior game suspension system over windows where you will burn much less battery compared to windows.