There isn't much breaking usually, I really don't remember big issues in my 15+ years self-hosting time. I have changed colocation place several times, some places have been offices with average office internet (without redundant links or BGP peering).
I can see issues, if you over-engineer and try build some microservice farm in some cloud provider, but simple physical server with DC grade disks in RAID and backup (tested and out of server) is pretty reliable.
Of course, when you really don't want to do it, then paying for someone else is reasonable, no issue with that. But its not fair to make mail self-hosting look like something very complicated and dangerous, I would say that modern web service stacks are more complicated and fragile. Lots of guys here are writing own internet facing software, handling customer data. Compared to that, using pre-existing mail server software isn't that hard.
this makes it stupid easy to set up your server. you have to do little config and you are up and running.
I decided to do miab because i had a necessity of "email aliases" in hundreds. none of these low cost email providers allowed that, unless i went with google workspace or 365 if i remember correctly.
rolling my own solved this issue and for the same price plus the "management headache" which i saw as a personal challenge more than a chore. so i am very happy with the results.
gmail has given me headaches in the start but if i send more than a few emails with attachments to gmail, they still flag all emails as spam so that is a recurring problem but not something i cannot live without
I can see issues, if you over-engineer and try build some microservice farm in some cloud provider, but simple physical server with DC grade disks in RAID and backup (tested and out of server) is pretty reliable.
Of course, when you really don't want to do it, then paying for someone else is reasonable, no issue with that. But its not fair to make mail self-hosting look like something very complicated and dangerous, I would say that modern web service stacks are more complicated and fragile. Lots of guys here are writing own internet facing software, handling customer data. Compared to that, using pre-existing mail server software isn't that hard.