I got a new phone yesterday; my old one, a perfectly functioning OnePlus 6, was forewarned by my carrier that it would no longer be supported so I needed a new one.
This creates a dilemma (though not the one I'd like to primarily highlight).
I could buy one specific to a carrier; this forces me to get a new one or trade it in, if I ever switch: this either wastes money outright or inadvertently by depriving me keeping the device I paid for to begin with.