You fell for the meme. I don't know about mid journey but at least SD is using images they got, it's not live learning new stuff, a model has to be made and it cannot learn live from the Internet. Basically, those images they paraded around are a troll, specifically made by people to mock them.

I agree with the posting stuff, pixiv for example specifically has a button you have to click if you upload something stating whether it's Ai art or not. If it is it's possible to filter it out(they have an option for that) and if you don't it clearly states what is AI generated and what isn't.

Seems like it's Artstation that needs to work out how to do their feed system, make it mandatory to declare, if people find out(there's tons of ways, one is just looking) you get banned.