Good quality phono preamplifier RIAA stages in standalone preamplifiers were more than accurate enough 30+ years ago. Their noise levels, overload characteristics, and THD were already at figures that were orders of magnitude better than the format itself was capable of.
For people who want to tweak everything and process additional parameters in the digital domain, sure great idea, but for someone who just wants to play and enjoy vinyl with the best preamplifier they can, I'd still be hunting down some of the statement preamplifiers made in the late 70s and 80s.
Someone with a complete digital phono front end can run a THD test from input to output at levels from a few uV to 320mV and see if they can beat the overall 90dB MM S/N and less than 0.001% THD (end to end) at 5V (20V max swing) out all the way out to
100KHz (not just a 20-20K RIAA deviation) on this preamp from 1983...
And these figures were from a very good, but nowhere near TOTL preamplifier.