Because of the kind of business Bahubali 2 did showing the true potential for Hindi films..not all south films are given the same treatment. Also they make it a point to mention "outright" Hindi films. Just the way how ABO is forced to mention non-Bahubali for all Telugu films to ensure their achievements are not undermined just coz of one phenomenon called Bahubali.
When you don't have majority films having dubbed versions then to make a fair comparison, you need to stick to one version. This is according to BOI. Other trade sites can follow whichever format they wish for.