I can understand that a guitar string bend includes semitones but if someone was going to play a scale consisting of 24 notes it would sound like they are just repeating some notes twice.
Just an FYI - if you were playing a quatertone scale, you would still only play 8 notes - I'll give you an example
The scale known as "Bayati" has one quarter tone - it is not tranposable - it always begins on D (sorry - did some research - it is transposeable to 3 other tones - can't remember which...)