Many people, even after being listened to, and even after having things patiently explained to them, still continue to enter someone else's email address into forms which will send sensitive information to that email address, and complain that they never got their important email, or that some "hacker" has "hacked" "their" email, etc.
In a perfect world this would not happen. We don't live in a perfect world and are unlikely to live in a perfect world any time soon, so we should not be asking "how can we be pedantic and tell users it's their fault for not reading the RFCs", we should be asking "how can we protect users from their ignorance of the RFCs".
(when I wrote this article, I did not expect that this would be the single most controversial line in it from HN's perspective, but I guess by this point I should have anticipated it)
Not in my experience. Showing compassion and agreeing with them that what happened is terrible and you wish things were different but you didn't call these shots back in the days and if they want improvement you can both go together and complain to google, the service which is actually broken.
Most people just want to be listened to. If you can do that, you'll earn a loyal fan, even if you don't do exactly what they tell you to when agitated. Some will even appreciate learning more about the email systems after the fact. They may even get the feeling you went above and beyond by offering to help them with matters outside of your site.