I almost never get spam outside of the spam folder. What I get instead is that half of the messages in the spam folder are not spam. This is actually even worse than just not having spam filtering. I still have to pick the spam out manually and ignore/delete it, but now I have to check two folders every day instead of one.
Which is some of the reason why I no longer use email much apart from Work settings.
Spam control isn't precisely an email problem, but a "system where arbitrary people not in my contact list can reach me" problem, same as telemarketers and SMS. Federated, open, lots of ways to describe it.
I agree that positively approving contacts is a great way to avoid the threat of spam, but that concept does have occasional downsides.