You're saying "e.g. pirated" but let's be real it's "e.g. Amateur porn where the women didn't know she'd be filmed/shared, upskirt videos, revenge porn, sleeping assault videos etc"
Users did not complain about the slow-to-react takedown requests at PH, but as was made clear this was an inadequate means to deal with non-consensual content, when videos can be reposted. Short of a more intelligent scanning system, the only way to do so was to nuke it all, which they did. And if they did happen to have a more robust automatic detection for that sort of thing, porn producers would certainly expect that it would be used for their content as well, which makes it completely redundant in the end.
If you don't want a wackamole game with non-consensual content, you can't allow piracy - this is what they realized.
It seems high, after the fallout from the NYT piece. Last I had read, unverified (e.g. pirated) content was all removed, leaving mostly studios and community power users. Like YT, piracy is the reason it flourished. Most immediately flocked to rival streaming sites that as of yet have not received the same level of scrutiny.