People don’t need to be dumb to do that. Being inexperienced with computers or confused about computers is enough to cause people to do a lot of things like that. There are a lot of people out there who are inexperienced with or confused by computers.
But my main point was that the brand may not be all that important in the first place even though it was included as part of the search term. The person making the search could’ve seen an ad and been intrigued by the product, but upon landing on a competitor site they may choose to buy a similar product from them instead.
If you are deeply into the kind of thing you are buying, you will make a lot of research to find the best one. But there are a lot of things we buy that we don’t care as deeply about, and where we may choose the first one that fits the bill sufficiently well.