Demand for support is because if you're undergeared, you're not coming a DD. You also only need 1 DD to kill any boss in the entire game(and a good corsair that does damage, or two dd's if you can't get a good corsair). Adding another DD to a party ACTUALLY lowers the damage if the DD gains tp slow, can't hit the mob, or can't do a 3 step skillchain with the other 2 dd's. I'm not joking, I've literally kicked a DD and then killed mobs 2-3x as fast, there's actually "too many dd's", and that's past 1+COR or 2 DD's.

You want 3-4 supports and 1-2 DD's. Everyone also wants to come to content with their 800 acc warrior/dancer dualwielding eminent axes/swords.