Ideally, we always want as many patches as possible to go into vanilla Wine instead of Proton or CrossOver first because we love free software and second because maintaining forked versions is time-consuming like mad. Actually, using Proton could be worse than vanilla Wine, because Proton is based on a past version of Wine which only gets updated every now and then (last Proton is based on Wine 5.13), so you are missing some development (on the other hand, sometimes developing features breaks stuff, so this could also go the other way around). As far as I know, Proton-specific patches are usually hacks targeted either generally at games or at specific titles. On average I don't expect specific merits using Proton vs using vanilla Wine for non-game applications. On the other hand, no other launching script is provided, but if you call the wine executable with the correct options and environment variables, it should just work. The launched script expects environment variables and other stuff from Steam, so it won't work without Steam. It is meant to be integrated into Steam, so building and using it without Steam might be a little less straightforward than pure Wine, but you can definitely do it.
