I really wanted not to comment this because there are many better authorities in the topic here. OTOH, I am sure I will learn something:
There will be friction. We are trading convenience for security. Paid smaller provider with human support is more convenient and probably enough for most people.
Also, the own-domain-approach is for an important inbox. Read as: it is business related, it pays for itself. It also allows you to set up as many addresses as needed. The receiving inbox is the critical part of email here, because it is often part of your logins.
Regarding your outbox:
>you're going to get stuck in spam filters all the damn time. Your email address will feel broken, sending messages into the void.
I try to remember this: Initially using forwarding. Send the message directly from your address to the recipient, and a ccc to a (more popular) forwarding address that sends the duplicate to the recipient, and starts with a clear: DO NOT REPLY TO THIS ADDRESS, and a "reply to" your own domain address. Your domain will eventually gain traction. This is a time investment to prevent a [another] catastrophe.
Other mention this point as an "SMTP relay service", which is a much better.
Others also mention that domains can be seized, which sounds less likely than Google or Apple randomly blocking your account.
Failed Payments and other Domain management tasks, that's something I only know as much as any other passerby.
Edit: inbox vs outbox