Comment by FireBeyond

Google has no problems "verifying" me with mapping to my phone number, etc. (Actually, it does, after a long and storied startup career, I can no longer create a new Google account because my phone number "has been used too often").

There's also the asymmetry of "you don't need to supply ID to make a DMCA claim, but you will to appeal it", which people can and have used to discover identities for more harassment.