Yes, but you can get exploration of ruins, crazed raiders, cannibals, etc. etc. in any city. While Fallout 3 had plenty of ruin delving, raiders, and cannibals, it also had some amount of civilization, organized trade routes, some big important faction in the area to bring stability, etc. etc. Philly doesn't seem to have that.
It also makes sense with their map. If we mark out were the known inhabited cities of note are, D.C., The Pitt, Great Lanta, Erie, Ronto, The Commonwealth, the rough location of The Abbey, we can see Bethesda has basically built a great loop of towns along the pre-war highway system.
Map: https://i.imgur.com/nisib8I.png
All of these places are connected in a giant circle along the pre-war highway system, with no two inhabited places of note being within a close distance of each other.
Much like how Fallout 3 gave us a very brief story about the nearby Great Lanta, I suspect Fallout 4 will give us some information about someplace like Hartford or New Haven Connecticut. Then we will get a DLC to the Abbey, and much like how The Pitt DLC told us of Erie, the Abbey DLC will tell us of some other place in New York State like Syracuse, or Rochester. This will complete the loop to so speak, spreading everything out over some distance that it doesn't all start bleeding together, like what would happen if D.C., Philly, NYC, Boston, Atlantic City, and all the others had survived, while at the same time creating a good pocket of civilization out of the upper east coast.
And even if they do skip NYC in Fo4, I doubt we will see it in Fallout 5. Bethesda clearly established what they considered to be the "major" and "important" wastelands of the east coast in Fo3. D.C., The Pitt, The Commonwealth, Ronto, and the Broken Banks, are what Bethesda defined as "the places everyone knows" as they are the only places mentioned multiple times, and spoken of as if you should know them by name, without any real explanation.
We got D.C. in Fo3, The Pitt in the DLC of the same name, The Commonwealth in Fallout 4, and Ronto likely got destroyed by the Lone Wanderer, which leaves The Broken Banks.
If anything, Fallout 5 is most likely to get set in Charleston South Carolina, the city with the most historical landmarks of any singular city in the entirety of the south, from Texas and Oklahoma, all the way to the Carolinas and Florida. As Bethesda set up a major "wasteland" of importance to be down there, and not NYC.