HSWL you are missing the point that The Greaser was making about setting the autobrake select switch to off.
What The Greaser means is that, if you do not disconnect the autobrake by stamping on the brakes or putting the speedbrake lever down, the autobrake will continue braking till the aircraft is actually slowed down to 0kts. Not very desirable since you want to turn off the runway!
If you do not have your feet on the brakes with the same pressure as the autobrake is braking and you put the speedbrake down the aircraft will suddenly lurge forward again (apparent feel) due to less braking. Not v nice sometimes.
Or by disarming the autobrake by manual braking you sometimes have to brake real hard to simply disconnect it, which sometimes even means antiskid activation. Not v nice either!
By switching the selector to off it can be done in a very smooth fashion