Ok i searched for ages and finally found is bulbapedia page.
Dexter appears as the MC and a Contest Judge of the Pokémon Super Contests in Hearthome City, Sinnoh in Pokémon Diamond and Pearl and Pokémon Platinum. He appears to be a kind man who genuinely enjoys his work, despite limited interaction with the player. His input appears to be somewhat more important in the Acting Competition than Keira's or Jordan's, as raising his Voltage to maximum gains the Pokémon's Trainer eight points instead of five. Also, he sits in the center of the three judges and has a heart under his name-Bulbapedia
The bolded parts suggest why as commented by others.
But im going to go with the fact that he gives 8 points instead of 5 in the acting contest which may explain it.