Yes, one might think that; I understand where you're coming from. And it would be a valid argument if mail clients and mail protocols worked differently today compared to a quarter century ago.

How mailing lists operate is constrained by how e-mail works. E-mail is very conservative.

(Yes, various things are there that weren't there a quarter century ago, like parsing out MIME-attached HTML and rendering it. Sure, SMTP is optionally authenticated and encrypted now. And in the routing and delivery infrastructure we have things like DKIM, SPF and DMARC. And we have DNS-based anti-spam databases. But by and large it's the same. The way a client sends and receives has not fundamentally changed.)

E-mail is a mine-field for people who think they have some great idea about some quick fix to a perceived problem.

About fifteen years ago, it seemed---to multiple people at the same time---like a brilliant idea to write an extension for a mail client (or a procmail script or whatever) to automatically answer all e-mails from senders who are not on a white-list, and challenge them to verify that they are real. That would solve all forgeries and spams, they thought! Oops ...