Can anybody explain to me in simple terms the argument about opening the floodgates for spam on iMessage if Apple would lower their restrictions? I just don't get it. If true, wouldn't this mean that every other messenger app with fewer restrictions or even alternative clients would have a massive spam problem? Anecdotally, I can't really confirm that.
Start with the conclusion that Apple's actions are necessary and morally good, find a reasonable-sounding but ultimately weak technical explanation and confidently present it as the only solution, then fearmonger less technical users into accepting the preconceived solution with all of its drawbacks using anecdotes and hyperbole.
Lastly, ignore or dismiss any evidence that invalidates your preconceived conclusions, like the fact that these "floodgates" have always been open [1] and yet people credit non-existent floodgates for solving the spam problem.
Anecdotally, the amount of spam I receive across Signal and Telegram is zero, and SMS is very close to 0, maybe one SMS every few weeks.