There's a lot of reasons for this. One of them is that it tends to be a lot cheaper to have one building in Denver to host support people than to have many buildings in every city.
Besides that concept, they're selling telephone and data services. It makes sense to -- you know -- make use of them.
When we had a telephone issue back in the landline days, we didn't load ourselves up into the car and go to a store to get help from someone in person; we instead used the phone.
(That may have been done by using the neighbor's phone, but whatever. We still have neighbors and not all of them are dicks. And these days, we still have cell phone stores for those who can't empty the water from a boot. The days of brick and mortar cell phone sales are not, at this time, numbered.)
I'd kill for the building in Denver. Instead I always get some extremely compressed voice connection in the Philippines.
I’ve been with US Mobile for years now and never once felt the need for a physical store.
Contrast that to my kid who is horrified by in person interactions and thinks that the kiosks at McDonalds were the world’s greatest recent invention.
Not to mention people with disabilities that make one form of communication the only option.
People are different and good companies try to serve them all.