Why do we need this button when visiting websites on cellphone platform? I mean, can't we go straight for the full site the same way it happens on PC without being needed to be redirected to almost a plain form of it with less information and search for that button? I don't understand. It would be great if you could explain it to me. Thanks in advance!
Well, the idea is that on a tiny screen with an imprecise pointing device, you wouldn't want the same UI as on a big screen with a very precise pointing device. On a PC, clicking a 2x2 button would be challenging only if you had some motor problem. Doing it a cell phone touch screen would be very difficult.
Another problem is a large portion of mobile users browse on a metered connection with a relatively low bandwidth cap. It makes sense to optimize a mobile site to use bandwidth more conservatively.