How come that NOS is better them NS new stock ?

There is a lot "tube equipment" threads on this forum. After hearing some good tube amps, Lamm, Hovland, BAT, Cary I could understand why people are buying and making so much fuss about it. I with every passing months closer to invest some money in "obsolete" technology :)
They really sound better then their modern SS counterparts. But I do not understand why people at any price are trying to replace their NS (new stock) tubes for NOS tubes. Do not we have progress in electronic industry? I believe that nobody is using anymore black and white TV, old picture tube should be better then new ones, is it not? But people seems to buy instead, new ones...
So how come, old tubes seems to be better for everybody here? How|Why they sound better?
Maybe SS on old germane transistors form 50's would be better too?
Maybe old resistors would be better too? It does not make any sens to me.