My experience says otherwise.
I've purchased a universal laptop adapter. Well, saw this and decided since my wife has a HP and I'm a Dell fan it would be great to only have to travel with one charger. Now I'm fully charged and hand it over to her so she can charge too (different voltage and plug size). You don't need to go to big box stores with price tags for a logo to get a version of this as I was appalled to see it was about $39.99 online.