It's not the accuracy, it is the lack of jitter and that has been possible and relatively cheap for some time. If you are feeding an async data stream, i.e. USB, wired ethernet, wifi, hard-driver, etc. then a basic oscillator with a decent power supply is effectively jitter free and rather inexpensive, practically free by audiophile standards.
It is when you start feeding synchronous data with varying data rates and trying to sync up two clock domains and you enter the realm of PLLs that it gets harder and a lot more expensive, and/or you get into techniques such as ASRC where you are beholden to the underlying math (and resolution) to convert between the two sample rate domains that performance gets far more variable (as does cost).
It is when you start feeding synchronous data with varying data rates and trying to sync up two clock domains and you enter the realm of PLLs that it gets harder and a lot more expensive, and/or you get into techniques such as ASRC where you are beholden to the underlying math (and resolution) to convert between the two sample rate domains that performance gets far more variable (as does cost).