This matters when you're hiding from the website. It doesn't matter if you're just trying to hide such things from the public.
It also matters if you're trying to hide from subpoenas to the website.
My HN account has no email. Not sure whether it would still be possible for a new account.
On Reddit and Hacker News, I don't need an email address to sign up. But also I use SimpleLogin to have a separate email address per website/account. Quite necessary these days when personal data is leaked by some company or other every day.