Redbook was 44.1Khz , so they could record digital audio on "Video Recorders".
48 Khz was for DAT, Digital Audio Tape - Wikipedia, the free encyclopedia - so you couldn't easily make a digital copy of a CD using DAT
2-35] Why 44.1KHz? Why not 48KHz?
My how technology has changed things.
The using integer multiples for sample rates is also known as "not making up stuff that wasn't part of the original signal" , or "better" if you prefer
You'll need some sort of crystal and clock divider to get a clock signal for your DAC, hence the need for multiple crystals as the clock rates are not integer multiples.