[smsm42]

I don't know how old are you, but before algorithms have mostly solved the spam problem, it was a real problem. If you have something like gmail, you could try recreating this experience by copying your spam folder into your inbox and trying to sort through it manually. I just checked and I get several hundreds spams every day - most of which going directly to spambox and I never see them. But it'd be a serious problem if automatic filters didn't work.

Recruiter spam is for now not nearly as bad as this - but with enough automation, it could be too. So "just delete it" is not a solution that scales. Maybe spam filters would catch it too, but then you'd risk missing authentic offers...