That may be because your address hasn't made it to the spammers yet. My address has been public for a while and not filtering meant deleting a few mails per hour. Even a Gmail-address I'm not using gets a good amount of spam, probably because other people have tried using it to sign up for accounts.
> I'm just not convinced it's necessary.
Well yes in some special cases dropping mails is not necessary. My mistake to assume your case is one of the common cases.
Yeah, because there’s less email spam now than there used to be.
https://en.wikipedia.org/wiki/Email_spam#Statistics_and_esti...
I've had to deal with Microsoft outright dropping everything from a domain (not on this server), so I do know it happens, I'm just not convinced it's necessary.