Are IMSI Catchers (Stingray) Still Something to Fear?

Stingray or IMSI Catchers are what governments use to track your phone in a particular area. In the past it was used to wiretap and it can be used to do geofencing; identify phones in a given area. For example it could track those entering a government building.

But changes in technology has really affected the use of this so I will explain if this is still a threat and how it would work now.