Agreed, SMS needs to stop being supported by handset vendors so people stops relying on it as the universal text platform.
When a communication system silently drops messages, this is unacceptable. But people are ok with it because they're accustomed to it being shit. The sender wonders why you never responded, and you are unaware they contacted you. Or the sender asks if you want to meet for lunch, and you get it 8 hours later. Group messages? I've compared phones on a table and we all have a different context to the conversation because each phone has different set of missing messages.
The messaging platforms are in silos and it sucks, everyone is annoyed about having 3-4 chat apps. But at least they work reliably, and that's the better alternative to garbage SMS.