As far as I understand (I was only working in the same building as uplay/Ubsioft connect) there were rules about payment processing (ie; all games downloaded through steam have to use the steam payments api: this is all I can find on the matter at a glance: https://steamcommunity.com/discussions/forum/0/1755779919109...)

Second; while you can sell your program in other places, you may not charge differently than steam. Which makes a lot of sense but is quite hard to grapple with in reality. I think there are cheeky “letter of the law” ways of working around this but obviously Valve don’t want that and then look for other reasons to just drop your entire catalog at random (this was not done by Ubisoft, despite the title and article claiming that: https://gamerant.com/ubisoft-remove-game-steam/)

After all; why go outside of steam if it’s not cheaper?