[Animats]

That's not the problem for something in the blog/message board/social network space. The problem is the ability to generate huge numbers of fake identities and spam. You can make all the Etherium wallets you want.

This is the standard spam problem.

[ETH_start]

That's a separate problem, and largely the same whether the sign up method is email or Ethereum account authentication. Spammers can always secure huge numbers of Facebook-accounts/email-addresses/etc.

What this does is make sign in easier and more secure, and obviate the need to keep track of passwords.