With the minefield of home electrical products out there, any magazine used as a guide is very useful. For example, if I wanted to buy a new TV, which most people do not do very often, I wouldn't have a clue what is currently available without looking at one or two magazines. Visiting an electrical store on its own isn't enough (it may be for some people who aren't into the best quality for their money), as I know they won't stock everything and will usually have offers based on their own criteria. If I see a TV within my budget with an excellent write-up in one or more magazines and then see that model on offer in a store, I would probably buy it.
Someone else has done the research for me because it's their job to do so, and I trust their opinion. Do magazines have an influence? Yes, very much so. Too much? I don't think so, sensible people make their own mind up.