Like Vampyre mentioned, most centers don't care about the league bowlers. They can make more off of open play, that is if they get enough people coming in and bowling. There are even some centers that have opened in recent years that don't allow any leagues and charge per an hour for one lane. They also expect to make more money off the the bar and snack bar from open play bowlers. This is despite leagues being almost guaranteed money. As long as nobody gets hurt they will be happy. AMF's President even came out and said it a letter to a trade magazine that their priority is the snack bar not leagues.
There are some centers out there that go against the norm though and treat league bowlers very well and the center managers try to help the leagues grow and will try to even recruit leagues from other centers. Unfortunately AMF got rid of most of the good ones in my area, I guess they thought they made too much and brought in managers with degrees in restaurant management.