Important things to know when assessing validity of these claims (and the claims are totally valid):
1) Bowls in factories are usually turned en masse. Setting up and tooling for bowl turning 'French-style' (which is also used elsewhere, but that's the term we use for it because it originated in France) takes a long time, so people turn a lot at once. It makes sense to turn all that you need for months rather than retool the line for another shape every few hours. Not all bowls are turned French-style, but if you're turning a lot of bowls at once, it's by far the most efficient way to do it (and the overwhelming majority of production at all of the larger factories is done this way). A typical run size for Savinelli is 2,000 bowls of a given shape at once. They don't use that many in a year for most of the shapes in their catalog (320KS, 606KS, 626 and a few others being exceptions, but they probably turn 105s every five or six years).
2) You have limited control on the yield. Briar is graded, so you turn more bowls when you need one or two of your grades, not when you're totally out. This leads to surfeits of certain grades (which grades are which and how things are graded vary from factory to factory, but the underlying issue is universal) over time.
3) The pipe industry in 1960 was about 50 times the size it is now. In 1980, Peterson made about half a million pipes a year. Today it makes about 60,000 pipes/yr. And it's one a tiny number of factories left; far more closed than are still around (and there are no pipe factories that make a lot of pipes that are not at least decades old).
Those three things in combination means, yes, there are piles and piles of old bowls laying around. Indeed, every real pipe factory--Peterson, Savinelli, Chacom etc--has high tens of thousands or hundreds of thousands of turned bowls on hand, some of which they don't really know what to do with at any given time. So, part of running a pipe factory is figuring out what to do with bowls that aren't presently being used that might be five or ten (or in the case of the Chacom factory 50 or 75) years old.
The story in St Claude is particularly interesting because you have lots of pipe factories decades ago collapsing into very few today. On top of that, there was a huge shift in pipe tastes (size, bent vs straight) mid-twentieth-century, which effectively orphaned a lot of small, straight stummels (which is how Ropp happened).
Also, yeah, a stummel sitting there for five years and a stummel sitting there for fifty just aren't all that different (the older one is likely a little harder to work with in the factory because of how it takes stain, but I don't think it matters at all to the smoker), but it is interesting that they're old and all that comes with it (shape, size, and the story that goes with it).
Finally, as a consumer, it's easy to get hung up on bowl turning = making a pipe, which is not true. As a percentage of the work and cost that goes into making a pipe, it's somewhere between 15% and 25% (depending on a variety of factors and varies from factory to factory). It's a bit like saying 'getting iron ore to sheet metal in spec is basically car manufacturing, right?' When you think of it as a discrete input into a bigger manufacturing process, the fact that it's done discretely (as part of an independent process) from the rest of production into which shelved inventory is fed, it makes a whole lot more sense.
