The main reason I have seen been used by the control is when two or more parallel rwys app are in use. They use distance and altitude as safety issues to synchronize both ILS capture. Lets say a pair of rwy 36 in use. One traffic coming from the west has been cleared to intercept the 36L at 4000’ and there is another traffic established on the 36R a couple of nm behind at 5000’. If the traffic intercepting the left loc over chutes during the turn, it could be a risk of collision with the parallel traffic. So, until the controller don’t see both traffics perfectly established on the LOC, they do not clear you for the GS.