The problem I have seen is when I need it most, due to a rare fiber internet outage, so does everyone else nearby and cellular data becomes saturated and unusable.
In locations where fiber is not available (like my place), cable is the next best option, and cable has a lot more unexpected downtime. I could see this being a good backup, especially for small businesses like retail shops that couldn't afford to have their POS go down for half a day.
I keep an old Starlink in a closet for this exact reason