Imagine if WhatsApp, Messenger, and Apple Messages were all fully end-to-end encrypted.
An authoritarian government comes in and demands that Facebook/Meta and Apple release a new version that is either not end-to-end encrypted or somehow allows the government to be able to see the messages.
Do you really think they will resist? Do you see Tim Cook or Mark Zuckerberg willing to have all their wealth confiscated and spend the rest of their life in prison on the charges of assisting terrorism (remember, we are talking about an authoritarian government. Remember also what happened to the Russian oligarchs to defied Putin, and the Jack Ma in China)?
So Facebook and Apple release the new version, and disallow using the old version (users get a popup saying they need to upgrade their app).
Do you really think any significant portion of users will not "upgrade" their apps to the less secure version and lose out on all their existing chat history and networks?
The people that would be aware of this and resist this, are likely using apps like Signal, Matrix, etc (apps that prize security over engagement and that have not come from the Silicon Valley tech giants).