I think it's a bit crazy to create a paid service on top of a reverse engineered product that isn't static. Indivious, NewPipe and other youtube frontends aren't going to create a paid youtube frontend, because they know Google could kill that at any point. Google could dedicate a full team to making youtube frontends non-functional.

Apple has a much bigger incentive to derail iMessage alternatives because they know that dumb parents have taught their kids how to live in a closed ecosystem and be slaves to Apple. 87% of USAian teenagers use Apple, which means it's only a matter of time before Apple becomes the dominant player on the market. If you want to keep making fat stacks of cash, the best thing you can do is control the market, which means killing of competition.

The only reason Apple would ever stop killing competitors is if it became legally and financially detrimental to do so. They'd have to reach Microsoft levels of antitrust and bad press before even considering backpedaling.

Everyone buying their products is helping Apple along to their goal of market dominance.