That is actually very treacherous ground.
The assumption that a quiet customer is a happy customer can be very misleading.
With sound libraries we often own a license to a great number of them. Many of those are being used only occasionally and rarely to their full potential. Hence we might not run into a lot of bugs or issues simply because we don't use them enough. Someone else however, in their particular workflow, is using that library much more intensely and WILL run into whatever bugs might be in there.
In this sense maybe none of my compositions would ever happen to include the note B5 of the muted 'Nose-blowing Alien Trumpet'. That note might be horribly out of tune, be panned wrong or full of audible artifacts, but I will never know it. Someone else however will. They may or may not report the bug, and in the end there is only a few reports reaching the developer. Still, the bug may be real and may pose a definite problem to those who use the library intensely enough. Those are then the bunch of "experts" who might not get a satisfying reply from the developer's support team and then take it to a public forum where, granted, the display of frustration may sometimes look out of proportion. But they may have a valid point and may not represent as isolated of an issue as it may seem.