he mentions CD which is 44khz/16 bit raw, which is basically as good as you need to faithfully reproduce the source signal for human ears

Still pretty irrelevant if you're listening to a track through Apple headphones or on a system with a bad front end. The point is that statements like this mean very little because there's a huge number of variables within the component chain that can have an effect on the end sound.

they apparently do not understand the Nyquist theorem and the way a DAC converts the digital signal back to an analog waveform. Even a lowcost chinese DAC gives less distortion than the whole process of recording / playing a record.

Again, by what set of standards?

I'm not just doing this for tit-for-tat reasons. If you're talking about imperceptible distortion and the Nyquist theorem then by those standards a high quality vinyl setup (observing as many possible solutions to external vibration as well as good clean elliptical stylus on a well balanced arm on a turntable with as inert a platter and damped plinth as possible, blah blah blah), the difference still wouldn't be noticeable. A clean record on a good turntable with a sharp stylus won't have any perceptible distortion. Mine doesn't and I don't have any hearing problems. The digital end of my chain sounds different, but not necessarily better. That is my view. Mastering of albums makes a huge difference, with re-mastering changing characteristics based on the lack of need to account for the limits of records, styli and the groove walls. Again, different, but not necessarily better.

I just don't think this argument is worth having in this day and age to be honest, mainly because of how ridiculously general statements become. Saying 'digital is always better' is just straight-up BS. There are too many variables for that to be true in every case. In a lot of cases, it's not true.