The parent is factually correct about the state of the world at time the decision was made but it is irrelevant trivia, given that Apple already supported SMS (an unencrypted protocol) and that they made a deliberate business decision to preserve the status quo of non-interoperability and their ability to falsely blame it on a dedication to encryption.

In what sense, that we literally didn't know how to do e2e across messaging networks? The Signal protocol existed in 2016 when Schiller argued against cross-platform (also PGP for 30+ years). Even granting that, offering iMessage on Android would satisfy most people and doesn't require operating across networks so any argument about feasibility rings very hollow.

https://www.theverge.com/2021/4/27/22406303/imessage-android...