Nostalgia plays a big part in this. Romanticizing about a past amp or lover elevates it's perceived status. Much like revisiting that gf we were so crazy about as a young man and finding disappointment, revisiting an old piece of gear disappoints.
20 Vintage Amps That Prove They Really Don’t Make Them Like They Used To
I found this article to be interesting and very educational! Enjoy!
https://www.headphonesty.com/