I was already a full time Linux user when steam came to Linux. Most games are closed source anyways, so I don’t see a problem in using a closed source game launcher. In fact as a general point I’m not against closed source, I use NVIDIA proprietary drivers since the performance is simply better, but I prefer open source software which is why my next GPU will be AMD. However the games are still closed source, so getting them from GoG, itch or Steam is very similar, but buying them on Steam gives money to Devs working on open source projects that improve game performance on Linux, so I’ll keep buying from them.