I understand the social lock-in factor, but there's no technological reason why people couldn't migrate to another app. Messaging apps, for 99% of the people,

I understand the social lock-in factor, but there's no technological reason why people couldn't migrate to another app. Messaging apps, for 99% of the people, are only supposed to deliver text and media from A to B. It's not hard in 2021 to develop such an app, even with E2E encryption and 2FA, even for a CS graduate. I'm appalled by the scarcity of real alternatives to WhatsApp, considering that a messaging app is a piece of software with low technological barriers. The solution seems quite clear to me. Force messaging apps to expose a public API, so that messages can easily be delivered regardless of the client used on both ends - XMPP used to provide exactly that, but both Google and Facebook decided to use it as a starting point and then gradually deviate from it with their own closed implementations. If one platform decides to bully its users with "let me read your messages so I can send you better ads or leave the platform", users would simply leave that platform without losing their contacts.