This isn't true. There was a guy who took 100 crankbaits from various manufacturers and tested them all with 100' of retrieve and 10 lb. line - - in his findings he noted that reeling the lures faster did not get the baits any deeper than using a medium retrieve speed.
Listening to crankbait designers, they seem to have the same theory - - once a bait reaches it's maximum depth, reeling faster will not get it any deeper.
Diving depth has little to do with the speed at which you retrieve the crank, a lure designed to run to 12 ft will run to 12 ft IF TIED to 0.28-0.31 mm line. Slower reels have more winching power, so instead of reeling in a bucket you reel in a crank, also, a slower reel will keep the bait running for a longer period of time.
It 's not about depth, it 's about LONGER time in the water ( where the fish are ) and easiness of retrieve, also, many cranks do not react well when reeled in fast, they just rest on their side.