Yes, and I didn't know that either until I tried it out. My regular FB account is "deactivated", but Messenger works just fine. They seem to have decoupled both products some time ago.
They removed that possibility some time ago. Now if you disable your Facebook account, it's reactivated as soon as you log into Messenger. Tried it just a few days ago.
Wait, that's awesome. I've been using news feed eradicator but now you're telling me that I can delete my Facebook account and still have a messenger account?
Does that messenger account work for "sign in with facebook" buttons? For example, the only way to authenticate with Tinder is a Facebook account.
No, you can't use the Messenger account for authentication. At least for Tinder I can confirm it doesn't work, maybe there's an OAuth provider for Messenger that no one uses, idk
No you cant sign into any other accounts with facebook, well you cant without reactivating it. If you sign into a deactivated facebook account even into a game, or something similar, it will count that as a account sign in and reactivate your account. If you fully delete your account, you wont be able to sign in at all.