It isn't only the stopset that aggravates the listener. It's also the type and number of like spots. For instance, KOOL used to run a long stopset at :50 and :10 punctuated by DJ blabber and the news (if you call three headlines and much in-studio hilarity "news").
The stopsets generally consisted of a series of motor vehicle dealer commercials one after another. Not only were they offensive in nature (lots of compression, loudness and yelling - kind of like the WWE) but they blended together and, once offended, the listener probably tuned out very quickly (if not actually hitting the button).
In the old days there weren't a lot of alternatives to this type of programming. If you wanted to listen to a particular genre you had maybe two, maybe only one, choice (unless you were in a large market). Now there are lots of choices and once the button is hit it generally doesn't come back.
Stations would do well to listen to their own product as the average listener does. There are ways to air commercials (which everyone agrees are necessary) so that they don't irritate the audience you are trying to hold on to.