I may be able to shed a little light on your PHL plight, though I am not a controller I flew in and out frequently and met a few facility rated controllers there. PHL is the busiest primary class B airport in the NE, busier than JFK, LGA, EWR, BOS, DCA, IAD. Normally that is not a big deal, you keep your arriving jet traffic at 12-13k until the downwind then idle descent from there, and departures go out right underneath at 10k until they are clear of the arrival corridors. Except in PHL...due to NYC airspace right next door, the NYC arrivals from the west and southwest are coming over just above PHL airspace, so PHL has everything coming in to their 4 arrival gates down low at 8,000 to get underneath the NYC arrivals AND the PHL departures which are at 10,000, and if PHL is departing east the departing traffic has to cross the arrival corridors above (if going westbound), especially jammed is the north sector with BUNTS to the NW and I think its SPUDS to the NE.
Long story short, they have to use more of their low altitude airspace for the primary airport than a class B airport that is all on its own, like CLT or ATL, you would never have jet traffic 30miles out at 8,000ft down to 6,000 unless they were on a long final.