Most teams use the POBO to add another layer to the front office; front offices have exploded in size over the past 20 years and more management is needed to handle all the scouts, analytics, development, coaching, etc.
I'm most familiar with the Twins in this regard. Their POBO sets high-level instructions for development, approach, etc. but it's actually the GM that is more public-facing and agrees to terms on most contracts, that sort of thing. The GM seems to be more of a day-to-day manager.