It is not a secuirty issue to have interoperable chat platforms, with e2ee to boot. This is solved, open source, and usable by anyone. They don't have to "work on devices outside of their ecosystem" since they will all be following the same chat standard. That standard will work on other devices, because those devices in other ecosystems will also follow the same standard. This is the foundation of how the internet works, from email to the web. Chat is no different.

I spoke pretty extensively as to why Apple locks out other phones from their system, so Im confused about why you think I don't understand it. They do it to build up monopolistic power. They want user lockin, to control the social network that is "iMessage." Once they lock users into their ecosystem, it keeps them buying high profit hardware. It's very apparent why they intentionally harm human communication by opposing interoperability. It makes them money.

That makes Apple scumbags, flat out. The same goes for all the rest that won't offer interoperability. It's not a reasonable choice. It's not for safety, or security or any other buzzword. They make it harder for people to talk to each other so they can make more money. Period.