Obviously not, but just don't push proton. They're a company that resorts to predatory tactics and has zero respect for their users.

For what's worth Lavabit (back before Snowden) had much higher standards than Proton when it comes to privacy and still supported open protocols like IMAP and SMTP. What Proton is doing is pushing for vendor lock-in at any possible point so you’re stuck with what they deem acceptable because it’s easier for them to build a service this way and makes more sense from a business / customer retention perspective.