At least one D&D supplement (BoED) puts a huge NEVER DO THAT sign on that action with wailing sirens and everything.
Why?
Because a Paladin Falling is tangibly making evil stronger. And in D&D evil as a force is actually a real thing.
A soul is something that should never be sacrificed according to more than one supplement of D&D. By extension anything that would taint that soul (say, Falling) should also never be done.
It ain't sacrifice to 'sacrifice' the one thing that should never be sacrificed. Moreover the people who usually whisper into the ears of a paladin that they should sacrifice the unsacrificable?
Usually they end up being from the, shall we say, deep end of the alignment pool. With a healthy dose of corruption in mind. ANd I don't know about you, but those folks usually don't have the paladin's best interests at heart.