7) You cannot compare a defensive midfielder with a box-to-box midfielder
Although both of these roles are quite specific in nature, they require different skill sets to execute perfectly and are basically quite different from each other, it is too much of a stretch to say that these differences are enough to make defensive midfielders incomparable to box-to-box midfielders.
At the end of the day, both of these roles require players to play centrally in the middle third of the pitch. In both attack and defence, both of these roles are quite similar and executing them well requires virtually identical amounts of endurance, agility, speed and technique. There are many more similarities in these roles than there are differences. Bad debaters magnify these differences in order to prove their points.
Therefore, it is incorrect to say, for example, that Sergio Busquets is not comparable to Arturo Vidal when both of them occupy virtually the same spaces for most periods of the match and take the same actions.