Whammy bar is continuous; for the use here you'd want something discrete.

Yes but....jeff beck used it often to find descrete notes

You have the wrong mental model because the guitarist chooses when to pick, when to mute, and when to bend. It can be either continuous or discrete.

Vocals are also "continuous" by your reasoning, yet most notes are sung in a "discrete" way.

A precise whammy bar technique can be accurate in pitch (arguably more accurate than frets due to their fixed equal temperament intonation) and you get the added bonus of no fret noise.

Fretless guitar necks exist for similar reasons. I'm actually now curious if there exists a guitar with a fretless neck that runs the full length of the string from nut to bridge.