Everyone has an excuse but you've gotta start somewhere. There are probably hundreds of ways to message people and we would all survive if Meta and it's products vanished.

I don't know anyone who uses messenger WhatsApp sure but messenger? Really?

Just use the Messenger app or messenger.facebook.com then, you won't see Threads promotions nor be exposed to other Facebook stuff

I use Facebook Messenger but not Facebook or Treads, just set up bare minimum profile and highest privacy settings.

I believe you can disable your Facebook account but still use Messenger, couple of my friends don't have a profile but can still message.