Why do old tubes sound better than current tubes?

I have great things about the new gold lion 12ax7 also, I am going to try them soon.

tung sol 12ax7 gold pins, very musical, sovtec lps 12x7 , very open great bass , but maybe a little less body than the tung sol.

some old tubes sound great, some sound like crap, some new tubes sound great, some like crap. Sorry ,but the notion that anything nos is better than anything new is just not true. I listen to the sound, not somebody's marketing hype.

because the people who sell nos tubes cant make money on new tubes. I have rogue m180s and have tried mullards, telefunkens, mazdas, GEs , rca cleartops, 5751 triple micas, and about five or ten I cant remember, sorry folks but the cheap as dirt sovtek 12ax7 lps is a winner, and so is the new tung sol gold pins, those are what I go back to again and again. the old tubes can sound nice and pleasant, but just dont have the resolution of the new ones, at least in my system. but now I cant brag and say I have three hundred dollar telefunkens in my amps either. I guess I will just have to listen to music instead.