Idk, it's a social media platform. User posts are already the product. I don't really see a difference in someone posting an opinion of theirs vs something they created. Maybe posting "hey buy my game" isn't the best look, but sharing something they made to users who might have an interest in their product is fine with me.

I can post advertisements for what I made on Facebook or Twitter, they also have ads. Reddit just allows the creator to select a larger, more likely to be interested, audience for their post beyond their current following. (Obviously some subs have rules against this to stop the constant postings, but I don't think it should be against Reddits rules in general.)