I'm sure it's a problem, and the degree of "problem" depends on the importance of the mail.

I think the real problem is that we are delegating to google the arbitrary decision of what is spam or not. Given that their core business in great part relies on syphoning info from users' mails, they have zero incentive to let users host their own servers and potentially bypass that data collection, and an actual incemtive to block as many domains as they can, for the sake of "safety"

I do, but spending more time ("full-time work") on it won't solve the problem, which is what I replied to.

The problem seems to be that Google does not even keep a reputation for my extremely low volume mail server, and the solution might be to set up automated emailing a couple of @gmail inboxes and marking-as-not-spam all of them there.

Even that wouldn't be full-time work.