Because even the impact studies paid for by the people behind the arena proposal say that the economic benefit to the city will be literally 1/5th of what they said it would be this time last year and called the proposal "barely adequate" and acknowledge that it will cause Displacement for the local community. The arena, when looked at from the best angle, is practically the embodiment of gentrification and will reduce one of the most walkable neighborhoods in all of the United States to a car infested wasteland and destroy the vibrant Chinatown that exists in the area today.
This one arena would take the place of dozens of small amd medium businesses directly and lead to pricing out hundreds more nearby.
We don't need a second meca to car culture (the existing arena in south Philly is barely any less connected to public transit but surrounded by a sea of parking) in our city, and especially not in the heart of it.
This was a rough watch but I really enjoyed it and I'm so glad that everything worked out in the end.