Old vs. New

I see a lot of threads on various audiophile forums that basically go like this: I sold my 5-6-10 year old speakers, amp etc. and bought new this or that and it kills the old stuff and sounds so much better.

I have listened to a lot of classic hi-end speakers, amps and preamps and also listen to a lot of FOTM stuff and to my ears a lot of the "old junk" sounds better, sometimes a lot better. Don't get me wrong a lot of the new gear on the market sounds very good.

So let me ask a question, why do so may people automatically assume that older gear sounds inferior to new stuff? Audio tech did not really changed that much in 10 y. We still have the same two ears now as we did 10 y ago? If something was good 10 years go why is it no good now?