Re: Quick, more boiling oil!
If you are of a certain age then the problem for a lot of people will be from all those harvesting emails in the late 90’s/early 00’s where huge email chains were used to find your Star Trek/Porn Star/etc. names.
This means that there are probably a lot of hash tables out there with a decent subset of personal data, and probably databases with links between personal info supplied above and surnames/emails.
Whilst emails could well have changed for many people and so this may be less of a problem these days, it would explain why some ID theft campaigns were so successful in the past, and why memorable personal data could be considered compromised or less secure.