Spam is still an issue. When you set up a new mail server, you are likely to be filtered by big providers because they will consider you as spam. I've personally had issues with Microsoft and a local provider. This makes self hosting or running a small email provider hazardous, which is problematic. I never had issues with Google and Yahoo though.

I guess spam and spam filters also have an ecological impact even if spams don't end up in our inbox.

And there are false positives too. Because of spam, we are likely to miss a legitimate message one day or another.

And I regularly see phishing on my professional inbox.

So spam is still an issue even if it is hidden, for several reasons.