You do not need parsers in order to see who fails core mechanics.
SE will never ban anyone if he constructively criticizes another player and offers solutions, nor will they ban you if you kick players.

While I do think a "training hall" would be nice, WoW did attempt such a thing at one time and it didn't make much of a difference.

Why? Because 90% of the bad players are not interested in learning/improving. They just want to mash buttons and kill stuff / get rewards. Present them with a challenge and they will simply abandon the endeavor.