Vintage tubes - facts, science, technology & empirical evidence VS. marketing, myth & hype

Sorry. Long post. I hope you find the premise interesting and useful. And hope my writing below is not too bone-headed. Please feel free to correct or point out any misstatements or errors in my thinking.

This is not intended to be a controversial thread. At the outset I am not staking out a position. My questions are sincere and are not intended to poke anyone in the eye. The ultimate focus of my question has to do with the performance of vintage tubes as they compare to current production tubes. I am asking because it seems to me that there is a lot of marketing hype & perhaps some myth and wishful thinking when it comes to vintage tubes. There is also a rich body of collective experience. And, it seems, consensus that certain brands, factories, vintages and specific types of tubes are better than their peers and are "worth" the extra money they command. Of course, the principle of diminishing returns applies here. Right?

Do measures of voltage gain, transconductance, plate resistance, noise and microphony tell the whole story? Are they sufficient for predicting performance? To what extent do they predict longevity? Or is longevity primarily a function of empirical collective experience? What about the materials science aspect of vintage vs. modern tubes?

It seems that every company that produces tubes works hard to refine their design and balance innovation with "faithfulness to the vintage design", production processes, materials to make good sounding tubes. Even so, not all tubes from a given factory will perform the same, hence the testing and grading relative to the measures above and the consequent sorting into hierarchies of ascending levels of performance and price.

It also seems to me that performance will be closely tied to the circuit design and execution. A solid design would, it seems, be robust and produce excellent results with a wide range of tubes. A poor design might drive a tube in a way that is hard on the tube or requires a very specific technical characteristic for the circuit to perform well. Either of these situations could cause a user to come to completely different conclusions about what vintage/modern tube is "good" or excellent.

I have read some posts on this forum from certain individuals in which all "modern" or current production tubes or tubes produced by certain countries are dismissed out of hand. This seems like prejudice. Or it could, I suppose, reflect accumulated frustration with a given tube/brand/maker/etc as it performs in a given circuit.

I suppose I’m ultimately asking those who’ve more experience and who have invested more $$$ in tubes and tube rolling across various kinds of equipment to share their experience and opinions.

Thanks, in advance, for your patience. I hope to learn from those who are willing to share.