The point isn't to verify the account, the point is to validate that the account belongs to a certain server. If I get email from alice@example.tld, then I now

The point isn't to verify the account, the point is to validate that the account belongs to a certain server. If I get email from alice@example.tld, then I now know it's from example.tld. If the mail is spam, I can ask example.tld to block alice, or I can simply blacklist example.tld. The important part in this is spam prevention, and that if I get an email from @paypal.com, knowing that it's real. What you're complaining about is another question, but not really relevant. Google always uses @google.com for employees, and if you get an email from that, it's real. This is about enforcing identification, not verification, security, trust, or anything else.