Warcraft III Why Blizzard gave up Naga as the 5th Race? 1 Naga vs 3 NE insane (娜迦 vs 3个疯狂暗夜)

I let Naga to play in custom games by replacing Human against three Insane NE AI. This could roughly explain why Blizzard didn't keep Naga as the 5th race. Similar as Fel Orc, this race is too powerful.