For Hershey it's pretty simple, they don't have a rink to call home. BB owns TPE and Palmyra while operating York.
I agree and would add that parents/players that were looking for more ice time to develop players were coming to PBK due to a much stronger commitment to Power Skating and a lot more options for skills/skating sessions at KLA to supplement team practices.
Stronger players the last few years that had aspirations to play Tier 1 were shifting to PBK around PeeWee/Bantam age as well which was slowly eroding HJB's numbers. Once AHF/Black Bear appeared, you saw the decline of HJB accelerate quickly in the last 12 months.
Will be interesting to see what happens as Black Bear prices are announced and I don't think the larger commitment to hockey that PBK requires is a fit for all families... some want travel hockey but are okay with just two team practices a week.
It comes down to what is best for each family's situation and expectation.