I don't know much about business, but I have noticed that most businesses do not subscribe to the "we do one thing, and we do it well" model. For example, the guy who invented those rotating perfect push-up things later came out with a travel version of the same product, and then came out with a perfect pull-up device. One assumes that he'll eventually come out with a perfect sit-up device, a perfect squat device, and a perfect screw-you-I'd-rather-be-fat device. Why? Because businesses--like relationships, as first noted by Woody Allen in "Annie Hall"--are like sharks: they have to keep moving forward or they die. (Woody says to Diane Keaton: "I think what we have on our hands is a dead shark.") If you only make one thing, customers may tire of your thing, or somebody may come along and make it better than you do, or a crazy lady in Peoria, Illinois may claim to have found a dead gerbil in your thing. As a business, making just one thing is a risky proposition. It's the classic case of putting all of your eggs in one basket.
Which brings me around, finally, to Guinness. In America, anyway, I've only ever seen one kind of Guinness: Guinness-flavored Guinness, on tap, in a can, or in a bottle. I've never seen a Guinness Light, a Guinness Winter Brew, a Guinness w/ a Hint o' Boiled Potato, or a Guinness anything else. It's always plain old Guinness.
Refreshing, but odd.