Maybe I've lucked out, but across the domains I own, as well as helping a few small startups clean up their outbound mail reputation, I don't see the hurdle in

Maybe I've lucked out, but across the domains I own, as well as helping a few small startups clean up their outbound mail reputation, I don't see the hurdle in running your own email platforms. I've got about a dozen domains that send and receive email and have never had issues when they're on infra I'm running in cloud providers. I guess it's the luck of the draw with the IP you get for hosting but the only real requirement is that the IP you're using is portable within the cloud/compute provider you're using (for long term viability between host upgrades). Beyond that I haven't found it hard to send mail reliably, even when bootstrapping a domain. Especially if you start from a place of decent email hygiene (e.g. DMARC/SPIF/DKIM/DNSSEC). I've even got a few lookalike domains that don't get caught up in filters because they've been maintained properly from the beginning.