First off, firefox is not part of KDE.
Firefox is Mozilla's product.
Secondly, I don't want advertisements at all anywhere in my operating system. They can stay the hell out.
I like linux because it sticks largely to a set of design principles. It is good because it's design is good. Things that suck are phased out, things are improved.
I'm sorry, but advertisements are an ulterior motive at best, and a surrender to mediocrity more likely.
Plus I don't give a damn about what companies want. Companies provide services and products. If I am interested, I will go look into what they have to offer, but largely I am uninterested in most of them. And I'm sorry, I don't want companies trying to invade my operating system. If I don't want your product, don't try to force it down my throat.
I know KDE is not an operating system, but I think if the case is that KDE is being motivated by companies, then KDE has become dead to me.