> But it worked (and still works) just fine with rootable phones on the network.

If the definition of "the network" is connecting to some LTE, sure, if it means being able to use RCS, or Google pay, or a banking app, it is much more questionable.

You attempt to cut the cellular chip out as the sole telecomm relevant part, but it is a fiction. It's visible today in bandwidth constrained environments like aircraft wifi that certain types of supposedly application-level traffic are not permissible (video calls). Conversely improving the channel capacity in general will require higher control of the user environment.