Umm, I agree with you, but that’s just human to human aspect. The whole email thing was never designed with privacy in mind, even ProtonMail has to keep all meta data about emails unencrypted, otherwise it can’t function. If I really want to keep something private, it can happen on Signal. So I gave up on emails, they are not private and they were never meant to be.
What is important to me is that my data is encrypted. Protonmail can’t parse my bills, amazon purchases or know how frequently I order takeaway pizza . Google could do it. How people I interacted with are aggregated is less important. I’ve sent emails to hundreds of people, but aggregation of received data on the opposite end does not show full picture of myself (well, plenty of my pen pals also have gmail, so… but I know 3 people who still use AOL!).
Certain set of email data is kinda one way, generated by the system/website and it’s my end that’s valuable. I don’t want to freely give it away, especially when online presence is actually huge chunk of my ‘personality’. This overused saying “if you’re not paying for the product, you are the product” is true.
So, I’m not disagreeing with you, emails are rubbish and privacy of communications is not improved by Protonmail. But I see benefits from not sharing my own email data with ESP and that was Protonmail’s selling point. And they are a Swiss company, it’s just too sexy.