So are you indicating that a machine with a concurrent use Pro license, can be upgraded through AGOL if the user has an account in AGOL and is an admin on the machine?
If this is the case, what if the org has a LM that only supports up to Pro 2.2.1 and Pro 2.3 is available through AGOL in the future? Would the user be able to update the Pro software and then fail to open the updated Pro software because the LM does not support the upgraded Pro version that was performed through AGOL?
Not specifically directing this question at you, since you might not have encountered this scenario at this point in your Pro implementation, but maybe someone else (ESRI personnel) might have encountered this scenario.