Transmission question

Ok, so i've read tons on here and elsewhere about the "3x3" drain and fill method of changing transmission oil. I have a 2008 TL base model w/navigation. Today I brought my car to a very reputable transmission mechanic who has tons of experience with hondas and Acuras. I told him about what ive read and what is suggested for draining and replacing the tranny oil. He said he would check to see if he could "pump" the oil out of the tranny by removing the transmission cooler line that connects to the radiator, as he's done this numerous times with success. I told him i hadn't heard of this before and left it to his experience to do this job. I picked up the car 4 hours later and he told me he was able to drain 8 quarts out by using this method. He did not use any aftermarket machine to pump the oil out. Im wondering why other people arent doing it this way? He replaced the oil with genuine Acura/Honda DW1 tranny oil. The car is shifting smooth with no problems, as i didnt have any problems to begin with. I also suggested he replace the pressure switches and he said it was a total waste of time and money in doing this. He said they are simple "on/off" switches, and DO NOT rely on any type of calibration as some have suggested.

So, as i said, just wondering why others havent done this method of changing the fluid.

Thanks

Alan