Re: Why is "SIM swapping" a thing?
I suppose it could be that, but if you have a network that doesn't use physical SIMs (CDMA network on 3G devices, devices with ESIMs, CDMA networks sometimes just at random), your only way to switch service to a new device is to have the carrier do so with the IMEI of the new device. You can't do so yourself. If they don't have a physical location near to you, they can do it over the phone, though in my experience they asked for some verification that I had the previous device (I suppose if that was broken rather than just old and being replaced I would have had to show up at their office). I don't know if this works on networks without this, as I've never had to call up a service provider to switch phones around when I had a physical SIM that could be swapped into the new device.