The context is medical regulations.
For example, there's a certain category of hot-button procedures that California believes are medically necessary but Texas will revoke your license for performing. To set up a shared licensing board you'd have to somehow find an acceptable compromise.
What's the alternative? Federal licensing would be good but poking around wiki it looks like the basis of medical licensing in the first place is "states' rights" so good luck with that. Reciprocity would also be good and hey! it turns out it's being worked on : https://www.ama-assn.org/system/files/fsmb-interstate-medica... https://imlcc.com