If you send an iMessage to an iPhone user, that has paid them, is there really much difference? This is more and more of a stretch.
And you’re not sending it - you’re asking Apple to send it for you, and using their resources in the process. And, as you haven’t paid them a dime, they can rightly say no.
Just as you did when I asked to use your computer for crypto mining.
Feel free to say yes to that, but understand that while you say no you’re also understanding why apple says no.