Yeah, but then you have to hold a second button for continuous AF instead... and continuous is more advantageous for action photography.
Like I said, there's a few ways to do the same things... use whatever suits you. I sometimes use BBF, but more often than not I don't. On my D5 I actually use 4 buttons for AF... The shutter is set to 153pt dynamic, the preview button is set to single point, fn1 is set to group, and fn2 is set to auto. The AF-on button is set to lock focus, and pressing the joystick is set to swap to spot metering... I guess I actually use FBF
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