In the gate-room dead bodies are not more able to keep the buttons pressed. This will keep many pugs out of fractals as they don´t know or cannot handle the right tactics.
Furthermore, not all classes have the same amount of block-/ invulnerability-skills. You reject these classes from fractals, although you stated every class should be able to do any content.
(P.S.: I am not posting this to harm you. I like your game and want it to become even better.)