I saw Fitgirl say that Steam versions are easier to patch later on. GOG patches seem to be a pain in the ass. I guess at least for her repacks.

So they can inject their versions with malware.

Cause fuck DRM. And sometimes because updates and game version on steam are different (e.g. skyrim version on steam support more mods than gog version)

On private trackers, it’s because # of uploads is one of the things that gives you a better user class. There’s other benefits too.