One of the handy things that Fastmail (among other providers) lets you do is set up a wildcard email address, so literallyanything@mydomain goes to a specific folder. Any time I want to sign up for some service I don't trust, I'll give them a specific email address. Long-standing practice, blah blah. Also, as my sibling said, "mash that unsubscribe button".

Less practically, it is pretty obnoxious for you to act superior about inbox 0, while pretending not to judge people who "let their inbox be overrun", and at the same time refuse to accept any solution to your inbox that isn't fully automatic. There are lots of options available to you besides leaning entirely on Google's machines of loving grace watching over your inbox.