[EGreg]

Can’t you just make the hosting site features only be for real purposes?

Like a link shortener which only forwards to a domain that matches the subdomain? Or only for watching videos and collecting metrics etc.

[internetter]

Any file upload can be used for unintended purposes, eg encoding files into static to upload to youtube and all other sorts of tomfoolery: https://github.com/boehs/awesome-cloud-storage-abuse