That has been the operating model for GTS for over 20 years. If you are not in Dallas, forget any upward mobility, let alone another function. In a round about way as an excuse to not post outside DAL - HR SrDir actually stated that the talent pool does not exist anywhere else....
My VP is not in a directional location, but their entire direct report staff is in BR. But any new job - BR.
Does not matter where your boss is.... only matters where they want the new headcount. If you really want a job not posted in your location - talk to the hiring manager directly to make your case. IF they like you, then it's up to hiring manager to make the case to their boss to allow the position elsewhere. You never know unless you try.