A tank alone isn't going to carry the fight... If most of the party is newer 50s running it for the first time, especially if it's one or both healers, and you run in and Leeroy Jenkins the boss you're probably going to die. The result of that is likely going to be raging at the healers/DPS then rage quitting the Trial leaving the group waiting for a replacement. It doesn't matter how old the content is...some people are experiencing it for the first time and deserve to do so just as much as us vets did when we first did it a year ago. The Primal opening CSs aren't very long so there's no excuse for not waiting for everyone to get out of the CS and then it's only polite to verify who, if any, is new. Running in when the healer(s) aren't ready is not only impolite but suicidal and detrimental to the entire party.