If this mechanism(link to a valid e-mail) is used to recover an account, is this considered a form of registration?
If you do provide one, it lets you recover your cookie based account is all.
The "account" is as throw away as you want it to be, basically.
Looking at the code, we do require something that looks like an e-mail, for recovery purposes (I assume, that code predates me by a bit). It is not, however, verified.
You can get the lion's share of a Stack Exchange's utility without registering, and this is quite intentional.