Earlier quoted context omitted.
If you are starting to corner the market and are able to use your leverage to block competitors in a way that threatens to undermine their business, then the EU (and to an extend the USA) will regulate you. I can flip your question around and ask "should you have the right to play dirty?". Which is what Apple has been doing, there's exactly zero good reason to not license out access to the protocol. I don't own Apple…
Apple has APIs for iMessage: https://register.apple.com/messages You can even build a REST endpoint for Apple to invoke when your business receives a message from a user: https://register.apple.com/resources/messages/msp-rest-api/m... Where's the playing dirty and undermining businesses part?
I'm too lazy to research why exactly Microsoft can't use this API to interface with iMessage and instead opting for a half-baked bluetooth solution, but there must be some hurdle.