Because the information recovery was never the problem.
These were the problem and still are in many cases:
1) Jitter in the digital signal, particularly from CD transports
2) Digital filtering technique in the DAC
3) Accuracy in the D/A and signal-to-noise ratio
It not only took many years to wrap our heads around these, it took many new technologies, protocols, techniques, new passive parts and interfaces to improve on them, including:
Low-jitter oscillators
Asynchronous USB interfaces
DSD and MQA
Improved digital filters in D/A chips, Apodizing filters and other custom digital filters
Ethernet - DLNA and RAAT interfaces
Teflon and polystyrene capacitors
Faster logic families for gates and flip-flops
Techniques for more accurate R2R resistor networks
Techniques for lower noise, faster-reacting voltage regulators
Upsampling and hi-res formats
Steve N.
Empirical Audio