Guys,
I have to say I do not think this is crap. The master cylinder piston will stop at a certain position in the bore normally. When you bleed IF you push the brake pedal to the floor you pass that position. That position inside the bore usually has a buildup of dirt/comtaminates. There is potential that this dirt, once the seal passes through it, can cause the seal to get damaged or deteriorate/leak.
I was made aware of this about three years ago at an NSXCA event, in a discussion with a very competent NSX mechanic out here in the east. He recommended that when you bleed ONLY push the brake pedal about half way down, similiar to the position it would stop in, if the system was closed.
Anyway this theory all made sense to me, so when I bleed brakes I only push the pedal half way down. I would say that depending on how clean you keep your brake fluid/system, this will be more or less of a possibility.
I DO NOT think that has anything to do with SpeedBleeders though. I personally use a "roaming" speedbleeder, since I have a piece of brake line with a one way check valve at one end. I connect it to the bleeder, open it up, jump in the car and start pumping. When I am done, I get out, close the bleeder and move on to the next wheel.
I always have a firm pedal when I am done, and I can track the car for two days and things are fine.
My $02,
LarryB