Audiophiles - probably the most prominent example of them all.
The big thing we tangle on is always digital vs. analog. Oh boy.... Zzzzz... I've cut tape and editing on analog sucks. Noise on analog is not ideal. Compression and 'natural' bottom end warmth are nice. But that's where it stops. Most of (all of?) these things can now be simulated by plugins. We don't even have to say digital has won because it's so obvious. Analog is there for the minority purists.
This debate has between us has taken many hours over many years. Oh yah, let's not forget vinyl too!..
I've had to recently redirect the argument to musicianmanship, which I feel is really where the rubber meets the road. It all starts at the source. If your source sucks, then you'll have some work to do to fix it. Stuff like autotune, sample triggers, etc. In this way, analog is better as it will demand more of the musician's performance. Hard to swap out the kick drum on analog.
All in all, I personally don't think any non-studio experienced audiophiles would know if something was recorded digitally vs. analog. There are so many things you can do now and unless you know those studio 'tricks', you can't even tell. This has already been the case since the 90's I think. Everything can pretty much be simulated, processed, filtered, chopped, moved, etc.
One great resource for all this is Ken Andrews. Look him up. He's got a lot of great stories and insight on recording.
My advice to my friend: learn the tools and use what make sense artistically. But debate for theory's sake is pointless in my mind.
I do think there's a few areas where analog still is a bit better technically (mostly from the musician perspective, things such as distortion and resonant filters), but digital is both often better and just so much more convenient for 90% of things. Those that embrace analog as a religion are rather annoying.
Now, I do remember in the 1980s there was a huge push of digital everything -- digital playback, "digitally remastered", etc. A fair bit of that at the time had major issues -- eg not very nice sounding DA stages, aliasing problems, etc. Perhaps this is where some of this attitude comes from.
Most of the anti-digital people I know fall into two overlapping camps - technophobes that don't know how basic DACs work (believing that digital audio means output of literal square and stepper waves into the air) or those that simply prefer older recordings from a point of nostalgia or artistic taste. Showing conclusively that some of their favorite records were mastered digitally before being compressed and filtered for LP is similar to watching climate change deniers try to reason via strawman and red herring arguments.
You don't have a vetted guitar, amplifier, mixer or a microphone? Yep.
That said, they sometimes have a point.