The fact of the matter is that game dev's are forced to do so much more in so much less time than in the past. Beta tests were NEVER there for every game, or even a majority of them. Less frequently now as well, as you have to pretty much ensuring your publisher mega bank in order for them to spend the time and resources on you to allow a beta test.
Also, more people play games these days. ALOT more play games these days. That is a huge increase in the chances of someone finding glitches, and the word of them spreading (due to the nature of the world these days with the internet) is ensured like forest fires. There are A TON of factors playing into this, most of which are out of the dev's team control.