I'm not really sure what the point of that would be?

Maybe my wife and I are in the minority, but we purchase exactly one brand of detergent, and we haven't switched in a very long time (that said, we switched to this detergent because it was less irritating to our skin than the other brand product we had been using).

We are pretty much the same with other products we buy on a regular basis; we don't brand hop unless there's a very good reason to, and sometimes we'll go out of our way to stick with a particular brand if we have to and can. We certainly don't do so because of advertisements (we don't watch television, and throw away the various adverts we get in the mail, and I only listen to NPR).

Maybe other people brand hop all the time because of a commercial they see. I'm not sure what to think about that, if that's the case

It's about selling to advertisers. It doesn't matter so much whether or not it would actually work, just that it offers ad vendors a new "blue crystals" feature to sell. Micro-targeting segments the market more finely, allowing higher prices to be charged overall while giving advertisers the illusion that prices are lower.