Fish hawg,
No doubt there will always be QC problems with anything, but I will still contend that this is a VERY rare occurance with fishing lines of any type or brand these days. The market is too crowded and competitive for this to be a common issue as much as fisherman depend on fishing lines in general. However the fact remains that many fisherman fail to appreciate the inherent differences or unique characteristics of different types of lines that are available to them. This is especially true of braids. The problem with braids is that folks fish them like they were fishing mono. Braids, by their vary nature, are actually less prone to "snapping off" than mono (all things being equal) regardless of brand. However braids are more prone than mono to abrasion and slicing (not necessarily cutting). These are often the root cause of failures such as you describe. It is not uncommon to find on closer inspection that some burr on a guide or a sharp edge on a reel or boat is actually the true cause of line failures that get blamed on a braid brand or type. In addition, the limpness of braids makes them particularly vulnernable to edges on open face reels when casting. Braid breaks from 3 to 10 feet out are a very good indicator of these kind of defects. Most stores today though will do whatever it takes to make their customers happy and therefore will often be more inclined to blame it on the manufacturer than risk losing a good customer over trying to educate them and insinuate that they might be doing something wrong. Thus the "Rule of Maxima".
Like anything there are always trade offs; for every benefit there is usually a weakness. Even the lack of stretch which can be desirable at times can also put additional stress on weak points like knots and cuts that might otherwise have gone undetected for a longer period of time with mono. But when it comes to sheer strength, pristine braids are incredibly strong, even too strong at times.