A few comments in the HN thread say it’s to offload load from the carriers service, but the original OP has neighbors broadcasting a hotspot (xfinity router/modems do this automatically when you rent a modem from them) so now its competing with their home wifi with no way to shut it off.
This breaks (off the top of my head)
-
Air Play
-
Air Print
-
Air Drop
-
Home Kit local control (and more?)
-
accessing your local security cameras
probably a lot of other stuff… How many people is this happening to I wonder?