@phd Ha! You're feeding into the hype!
Class A and Class AB will never be obsolete in the second-hand market. Sometimes I wonder if it's not wiser to score a Denon/Yamaha/Pioneer/Onkyo/NAD amp for $100 on the used market and pair that with sufficiently good speakers and call it a day.
I might be diverting the conversation towards budget gear and vintage gear. But I would love a comparison between a vintage A/B amp and a cheap China amp using class D.
To me the high end is clouded in a veneer of romanticism and craftsmanship. For example people who buy expensive tube amplifiers are not interested in getting the best performance metrics. They're looking for a unique experience. This may explain why some audiophiles have several different amps/speakers/turntables and DACs for different experiences. It's just nice to switch it up.