Explanation of why my question is not a duplicate of What is the best way to store my tent?.
I am specifically asking about an aspect not addressed in the earlier question or any of its answers: does prolonged storage (several years, not several months) in its stuff sack without ever taking it out affect the lifetime of a tent?
We have two tents, one smaller than the other; we use the smaller one when we expect mostly fine weather. We use the larger tent only when the likelihood of bad weather is high. Thus, the larger tent may remain in its sack for more than a year. Once, after prolonged storage, the rainfly failed.
Is it likely that keeping the tent in its stuffsack for a couple of years was the cause of the failure, and that its exposure to UV over its years of use made it really inadvisable to store it this way?