I agree that busy wait is not good, but I could think of one rare situation that a process wants to busy wait instead of blocking:

When a process greedily wants to capture an event as soon as...

a = b = 0 # shared counters
sem(0) # semaphore initialized to 0

func_A: # code for type A process
a = a + 1
sem.V

func_B: # code for type B process
b = b + 1
sem.V