There were many huge problems with the way filtering was handled.

Various filter types were scattered all over various drills, making it very difficult to know where to find what filter. It was not possible to apply the filter universally outside a drill. It was not possible to tell how many and what filters were active at any given moment. And as if that wasn't bad enough, the act of filtering filtered out data, but not objects in the map.

This was causing great confusion and many users were convinced that filtering does not have any effect (while it in fact had, misleading them for the second time...).