I have a power tap wheel for track. I use it for aero testing and measuring efforts. For example, I can do flying kilos at the track at a certain power level depending on the training goals.
I can also do a flying kilo and have a timer calling out lap times. I may want 18 second lap, 250 track, which would yield a 1:12 kilo. However, I can set the target lap time to whatever I want.
So a stopwatch and another person to time efforts is very helpful on the track and may be more significant than power measurement. For example, a 1/2 lap time after a full power standing start is a good measure of a sprinters start and acceleration. One can choose different gears and optimize the 1/2 lap starting time. However, a power profile can also be useful in showing weakness off the line or during initial acceleration.
One thing I have found is that the TSS generated from the Training Peaks and other software is bogus for the track. IMO, the efforts, especially full power sprints, are very fatiguing but do not score a high TSS.
On the whole, IMO, power measurement is an excellent tool at the track.