Like many others, I gave up on self hosting email when I realized Gmail and Outlook would always mark me as spam, if I even got delivered. DMARC and DKIM did nothing, I think the datacenter IP was just blacklisted. Ostensibly there are ways to get it unblacklisted but man what a pain the ass for the whole process.

I had some email bounced by gmail, had to hardcode the ip addresses in the SPF records.

I think gmail can just gradually bounce self-hosted email and people will give up and move to their service.