Having to bend up to a given note each time you need to hit it will be slower and less precise.
Generally the bend is done after the fretted note is struck as well. I guess it would be possible to always pre-bend to a given alternate note if you wanted a constant tone, but it definitely seems like working against the grain of the tool versus just using a fretless instrument.
Eddie Van Halen was known to do this, though he was admittedly a freak of nature. He tuned the B string a few cents flat so that barre chords played up the neck would sound more in tune. If he needed to play, for example, a D chord in first position, he'd bend the D fretted on the B string slightly sharp.
There’s a video of a Van Halen concert where the synth track for Jump was played back at the wrong bitrate. Eddie worked furiously to find it on the guitar but couldn’t. It’s pretty wild to watch.
Generally the bend is done after the fretted note is struck as well. I guess it would be possible to always pre-bend to a given alternate note if you wanted a constant tone, but it definitely seems like working against the grain of the tool versus just using a fretless instrument.