Giving in to sites refusing to take custom domains is what leads to for example self hosted email being so difficult now because the big 3 run the show and defacto control internet mail.
We should also stop "dumbing down" to a point of sacrificing security and anonymity because people are unable to take down an email address in 2023. Remember when Google and others wanted to get rid of urls and use just words because "it is too difficult for people to remember urls"?
People used to remember multiple phone numbers in their head!
Humans can learn, we should stop encouraging brain lazyness, it leads to mobs of idiots who think another man won the presidency no matter how much evidence you provide that it's not the case.
The whole concept of "custom domain" is absurd - a domain is a domain... Or why does Google use that google.com custom domain instead of a respectable one like ibm.com ?
→ their problem, not yours, don't take on.
- refuse to send a password reset…
→ is it a payed service? request moneyback, involve customer protection. is it free service? no warranty for you. don't rely on it heavily.
- say out our your email address to a non-technical person…
→ don't connect to people who can not copy ascii letters, written or verbally. my daugther is 5, she can. "@domain" monoculture is bad.