I agree.
Also, there isn't a 100%, knock down, drag out argument for supporting a particular sports team. As in, you MUST choose this one because of capital R Reason, but of the arbitrary options for doing so, going local makes sense. Supports your region, gets you involved in the city, brings you closer to friends and family more easily (because everyone is on the same "sports page"), supports the local radio/tv industry, shrinks down the amount of sports news (can't report on every team as NBC Philly), and so forth.
If I'm from Philadelphia and I choose to select the Alaskan Snow Pirates, that seems friggen weird. The people that do that often double-down on supporting those teams too.
Because it isn't 100%-- that's why many people "allow" for special dispensation for supporting out of market teams. Like if your dead father was a Giants fan and that's all you watched -- okay, we get it.
But, ceteris paribus, if there isn't an outlier, you should probably support the city whose circle you're in. It brings a city together, rather than having 1 more reason to divide people.
There are actually some decent moral arguments for supporting local everything (basically, you can't save the entire world, nor can you accept responsibility for the woes of the entire world, but you CAN try to make your local area better, give it local support, and if EVERYONE was supporting locally, the benefit would be global as a nice secondary effect).