Because interoperable communication systems are supposed to be core to getting to use all that government-allocated public infrastructure (like phone networks, wireless spectrum, etc). That Apple intentionally degrades the experience for interacting with non-customers is "malicious compliance". Only implementing the oldest standard at the minimal level is worthy of ridicule.

If AT&T started introducing delays, message duplication, degrading image and video quality, etc whenever you messaged a non-AT&T customer, HN would be up in arms. But because the world's most valuable company does it they get a pass?

I don't care if Apple let's me use iMessage. I care that they won't implement RCS or let users change the messaging protocol handler on their phone purely for anticompetitive reasons.