Hmm, wouldn't blocking IPs be overly broad and risked affecting regular users? Considering that IPs are scarce and constantly recycled by ISPs etc. Blocking device identifiers sounds more targeted and, for that reason, realistic.
So your point is Apple can presumably distinguish between an actual iOS connection and Beeper's connection by looking at "how many connections per IP"? Still seems prone to false positives to me, unless there is something else I missed.
(Upon re-reading the post, I realized that the phone number registration is actually done by Apple. Wonder if this might provide another basis to block Beeper, i.e. all this SMS infrastructure is not cheap to maintain and Beeper's integration is arguably using it in an "unauthorized" way.)
They don't need to break it completely. If Beeper is unreliable, nobody is going to pay for it.
The amount of legitimate users it would affect would be trivial and can be taken care of by customer support.
The benefit of that is that I can then, at that point, verify if we’re dealing with a legitimate device or not. Geniuses at Apple Stores can obviously do this physically, and remote support has the option to run remote diagnostics and even share screens.