This meant that everyone had one, you didn't have to go sign up somewhere else. You still could if you wanted to have a URL that didn't have your ISP's name in it.
And few people used the ISP mailbox because you couldn't take it with you when you left. Hell, I got my gmail during the invite only era
Personal pages were once an option in those people's minds (i.e. get around to it later). Then it got bargained down to social media profiles. Now anything at all has become a liability and the juice isn't worth the squeeze.
I think that's what they mean.