There is no authority to define video games genres - AT ALL (it's not like there is a DIN/EN norm for it...). Wikipedia is surely not such an authority neither. In the end, there are ONLY personal opinions and definitions about that one and that's the point.
Did you check out the sources? They were pretty reputable and professionally written. I don't trust wikipedia if they have bad/no sources :p There are actually papers and books written on the subject of game design and genres, just like for everything else, so it's not like nobody knows what they are talking about.