A lot can be said about the clusterfuck of the Philly Popeocalypse. And I imagine some visitors are enjoying themselves! But, basically, it reflects two major ways that even people who live in cities and run things get it wrong.
1) Get them in, get them out events do nothing for the local economy or the local quality of life. This applies doubly to football stadiums, aquariums, and numerous other "attract visitors" initiatives that attract visitors only to a specific spot. There are no spillovers if your planning goals are about getting people to an event and then getting them out again.
2) Cities see their own residents as the enemy. Pretty sure a big event like this would have done quite well if locals had not been told to run screaming from the city if possible so that visitors could enjoy the enhanced security measures with fewer troubles. 1.5 million people live in this city. A few more of them probably would have been interested in the whole thing if they weren't treated like prisoners in their own city, complete with national guard members stationed at every corner, and effectively told they were idiots for sticking around for the weekend.
If that's the approach that is necessary for security reasons or whatever, there are nice big parking lots at the stadium complex which can accommodate such things.