Thass, you sound like some of the engineers we work with here.
Perhaps you should pay some attention to what they're telling you?
Mostly, the ones who fail to recognize that I've been a technician for over thirty years, and I've seen ample cases of problems arising from skipping over regular maintenance.
I do not doubt you, but you are moving from the specific (in this case exhaustion of a chemical reaction) to the general (all regular scheduled mainteneance) back to a specific (regulators) that you have a small fraction of my experience with.
Keep in mind that, in my job, I'm paid the same whether I work on the equipment or not. It's no skin off my nose if the engineer lets me do the preventative maintenance on his equipment or not; I'm paid by the hour and not by the job. I'm just as happy to be left alone in my lab, as to be elbows deep in equipment that's older than my grown children.
It sounds to me like you have a workplace issue that has no relation to our discussion here.
While there may not be charted empirical data on the deterioration rate of o-rings, for example, a good tech will soon see a pattern emerging on the equipment he works on. In an area like Tucson, such rubber parts tend to break down faster than they would in cooler, more humid areas. Our hot, dry air is not conducive to rubber and plastic parts holding up well. "Dry rot" is common around here, and a good reason for having such parts inspected and replaced on a regular basis.
I'm not saying that parts should not be replaced. I'm not saying that regulators should not be inspected. I'm saying that yearly rebuilding is wasteful and there is no empirical evidence to support it. In point of fact, most of us who have looked inside of hundreds of regulators per year or been responsible for those regulator's maintenance do not support the idea of a yearly rebuild, rather we favor a time and use based inspection schedule combined with performance monitoring by the end user.
A failure doesn't have to be catastrophic to cause problems. A cheap part that would be easy to replace - if you had it - can bring a variety of activities to a halt, or at least, take much of the fun out of them.
If you have a trip coming up it is only reasonable to have an inspection done and any needed servicing far enough in advance to permit a few dives prior to departure since there's a much higher likelihood of failure post servicing.
You can call it fear mongering if you want, but just like regular maintenance of an automobile helps prevent premature wear of the engine, or failure of the brakes, or a loss of power because of clogged filters, or whatever, regular maintenance of scuba gear can keep things working properly.
Reulators are not engines or brakes or fuel systems; it is illogical to extrapolate from a car to a regulator.
Perhaps you should read you own signature line. I've been in repair and maintenance since I was 18 years old, performing such tasks for the Air Force, for a major defense contractor, for a cable television company, and on my own possessions. I've had 31 years of uncomfortable thinking on this subject, so I'm rather comfortable in my opinion on it.
You have been operating in a "need it or not" servicing environment on systems that both extensive failure mode analysis, part tracking, and mean time to failure testing and data gathering are done.
If we must perform the obligatory logical fallacy known as an "appeal to authority," then consider that I've had more than thirty years of being responsible for hundreds of sets of exactly the type of equipment that we are discussing here, not systems that have little or no resemblance to diving equipment. In my early days I was a firm believer in yearly rebuilds, but experience has taught me that, at least with respect to regulators, that approach is both wasteful and creates more problems than it solves. So either I'm way off base, or the community is being sold a bill of goods by someone, with folks like you an honest regulator techs being mislead down the primrose path.
