Whereas once the area was sufficient for both sides, there’s now only room for one. (There’s no hint of the fact that San Juan Hill was, in fact, a predominantly Black neighborhood.) The filmmakers’ attempt to pin down a cause for the Jets-Sharks rivalry reflects their more general shift, in the new film, toward facile psychologizing.
The speaker is mostly just talking about a specific topic here and why the filmmaker has not done a great job with the racial problem.