It kinda does, though. It's why I stopped self-hosting. I bet if you emailed my gmail address it wouldn't come through, even through no fault of your own.
You can have DMARC, SPF and DKIM all correctly configured on a clean IP and some mail server at Microsoft will still drop your mails because it's having a hard day and it feels like it.
This makes it something that the average person cannot do; you're suggesting something that already requires more time and resources than 75% of the population has access to.
If you're serious about this than go talk to a non-tech person and tell them to self-host email and see how they do. Look at their challenges, build a solution and then offer it.
Please don't try changing the goal posts by introducing "non-tech" people into this.
That's not at all what the conversation is about, and routing through an external place removes a whole bunch of hassle compared to setting up and maintaining outbound email.
You might not like it for some reason, but that's on you.
If you need a third party to deliver your mail on your behalf, are you really self hosting?
What's the point? At that stage you've already conceded the deliverability problem so now you're just wasting time administrating dovecot and keeping up with security patches.
You can have DMARC, SPF and DKIM all correctly configured on a clean IP and some mail server at Microsoft will still drop your mails because it's having a hard day and it feels like it.