Not everyone uses Gmail or a modern email client that understands the one-click List-Unsubscribe protocol, so senders must include an HTML unsubscribe link in the body of the email in order to comply with relevant rules in all jurisdictions. That link, unfortunately, can fall prey to the shenanigans I mentioned above.

I understand the parent's sentiment because we all want to unsubscribe from unwanted emails. But technical standards can't distinguish unwanted emails from business-critical emails. You could legitimately cause someone damages by silently unsubscribing them from an important news feed. (Imagine that you silently unsubscribed an open-source maintainer from all github notifications!) Even worse, this kind of vulnerability disproportionately affects senders who try to follow the rules and make it easier for people to unsubscribe. Spammers don't care and keep spammin'.

Ideally, an email would have both a one-click List-Unsubscribe header and an HTML unsubscribe link in the body. The latter need not be one-click, and in fact, if it's anything remotely important, should not be.