Because having seen the penalty incident from Saturday, even if that had been in the area it shouldn't have been a penalty!
I've been telling my lad for a while that half the pens given these days should be indirect free kicks for obstruction,and the regular one where the defender shepherds the ball over the deadball line whilst obstructing the attacking player by whatever means possible would also have been an indirect kick,(although inside the area in some cases),but looking at FIFA's online rule book it looks as though obstruction has ceased to exist,I don't know when this happened or why,but it seems to be the case now.
Its been replaced by giving a freekick to the goalkeeper if you make any sort of contact with him whatsoever, and certain challenges only being given as a foul if they're outside the penalty area. How many tines do you see a foul not given in the box which would have been given elsewhere on the field, its as though the referee thinks that a penalty is too harsh a punishment sometimes