I believe your analysis is to some extent is incorrect. First of all, the state owned tea factories were still producing under the auspices of the CNNP; however, not to the level that they are today under private ownership. Secondly, you have to remember, that pu-erh in the 1980s and well into the 1990s, was still a very common commodity which was typically localized in one area of Yunnan . As a result, old stock was not uncommon to find. Furthermore, you have also to take into consideration that the metropolitan areas of China believed that pu-erh was a rustic drink for the credence and not part of the culture of the growing middle and upper class and therefore only drunk by a particular few-relatively speaking. However, during the SARS outbreak, some believed that pu-erh could actually protect individuals from the disease. As a consequence, some enterprising Taiwanese business persons bought up nearly all of the old stock in Yunnan essentially monopolizing the entire aged pu-erh business. This factor coupled with the ever increasing popularity of the tea worldwide explains the astronomical prices we see today.
Wyardly is correct in that Dry storage was not recognized until the infamous '88 beeng cha, so yes, most of the older stuff is and was accelerated stuff with the use of high humidity. But then again, they didn't care about dry stored stuff or even knew what it was. They just wanted puerh to drink and was not as academic of a subject as it is today.