The problem with infinite, easy to create identities leads to a well researched attack, known as a Sybil[1] attack.
If there isn't some type of cost or friction to creating identities, you will have a lot of bad behavior, full stop. This has been shown time and time again, so it's basically a non-starter. I don't want to be part of any social network that has this feature (infinite identities), its going to eventually turn to shit or require intense moderation (or both!)