Here's the % chance to win with certain comps;

- 5 dps vs 4 dps 1 healer > very big chance that 5 dps team actually wins because they outweight with damage and can easily nuke healer, making healer effectively dead 90% of the time. Specially if healer is WHM that is easily the worst one for defense. Now if 5 dps team doesn't have dragoon, dnc, vpr, monk / mch or osmething serious, then yeah its quite bad.
- 2 tanks vs 1 tank + 1 healer > 2 tanks team has slightly more chance to win. Specially if they are drk + gnb. If latter team has Scholar, then they may have a chance.
- 3 tanks combo can also be seen, same as 3 healers vs 3 healers which is a snore fest.

Ninja is a big subject. Can be a frontliner as many players proved it. Doton gives damage reduction, have big shields. Can absolutely survive insane burst as ninja, so it's not that bad. LB is also one of the things that can change the course of the game and why people still hate this class + hunt it down first.

For RDM I agree, it used to be a class that only few would play because of black / white stance but now it has been degraded to the point that everyone can spam buttons. DNC on the other hands is annoying when in perfect comps. Your 5 dps with dancer is going to win over any tank or reaper. Specially if dnc is combined with drg, monk, blm, mch.

Matchmaking cannot be adjusted due to lack of playerbase so players must try to win the "Impossible". Scholar is just too busted together with astro and they both make wins for teams that would otherwise lose hard.