Can't speak for anyone else, but personally I'm getting fed up of legitimate personal e-mails going missing even when sent to long-time friends I've swapped mails with on numerous occasions, only to find they're in the spam tray. These are plain text messages, all sent from the same very small pool of mail servers, with correct headers, consistent From: address that really is me at a personal domain I've held for years, etc.
I should not have to jump through non-standardised and somewhat broken hoops like SPF and DKIM just to get a goddam e-mail delivered to my friend. When you reach that point, it's not your e-mail client or domain registration that's broken, it's the receiving e-mail system that's so paranoid about spam that it's regularly diagnosing and (silently) rejecting false positives.
I should not have to jump through non-standardised and somewhat broken hoops like SPF and DKIM just to get a goddam e-mail delivered to my friend. When you reach that point, it's not your e-mail client or domain registration that's broken, it's the receiving e-mail system that's so paranoid about spam that it's regularly diagnosing and (silently) rejecting false positives.