Seems like questionable advice - sounds like a great way to accidentally drop a bunch of weights to the floor if you're at all uneven with your bar path (not at all unusual when fatigued).
Not only that, but even a little shift in the weights can cause problems with your lifts. Warmups (135 or so) I'll leave them off, but anything over 200 I'll put them on.
Then you really have to look out for the recoil as the suddenly-unbalanced bar whips around.
Bench press at any significant weight just flat-out isn't safe without a spotter.