I don't know that I would characterize the likes of Heiser and Lawrence holsters as "cheap, one size fits all". True, some vintage holster may fit that description, but many do not.
Like others, I have quite a number of vintage holsters and I am willing to stipulate the quality and the precision of the fit varies somewhat, like the better brand holsters of today. I have quite a number of those also, many from very, very well known makers that vary in precision of fit. Most of the better-brand vintage holsters were designed to fit specific firearms, so the "one size-fits all" simply is not true.
It is true that any holster from any maker will contribute to wear on any blued gun to some degree or another. We might also agree that the use of any holster will "accelerate" wear to bluing. I have a two 99% Colt Woodsman MT's that will never, during my stewardship, see the inside of any holster for that very reason, EPS's (or anyone else's) apparent quality notwithstanding. It is simply a matter of repetitive friction localized to the high spots on the gun that contact the holster. So if one is fastidious about wear on collector grade guns, then holster use should be rare or never.
But it is far from axiomatic that older holsters were mere loosey-goosey scabbards that will necessarily result in accelerated wear compared to more modern offerings. I have a another Colt Woodsmen that has seen extensive holster use in the field over a period of nearly 30 years of use in a Lawrence and the accumulated "holster wear" is no more significant than what I might expect from a high modern holster that is hand boned fto the degree that it permits no internal movement of the gun inside the holster after holstering.
Do I believe that Heiser, for example, is equivalent to EPS in terms of precision of fit? Maybe, maybe not. It would take a side by side comparison using the same gun to establish that, and I cannot do that. I do own examples of both, but not one of each for any one gun. I don't know that the relative difference between an EPS field holster and a Heiser field holster in good condition is all really all that significant. The quality of each is superb. I don't agree that the older holsters are not worth having because they are cheap and ill fitting.
And I am not so sure that there is widespread agreement that lining (which Heiser and others offered, by the way) will substitute for a good, tight fit to a specific model of gun.
I do agree that it is all about fit. But I disagree that the older holsters do not meet a reasonable standard in that specific regard.