To be honest I think that the problem you're describing has to do with perception from the new player and thoroughness from the mentor. It's a two-way street. As a mentor, you need to be able to put it in layman's terms at times since some people may not know what DWT means, even though it means Dreadwyrm Trance. The same goes for explaining rotations. Generally what the sprout needs to do is try it out and work on muscle memory from there.
So, let me go down the list here of what you're describing as 'toxic' behaviors:NN exists because FF has a steep learning curve for a new player -- both for someone who has played 10 different MMOs in the past 20 years as I have, and someone new to the genre. It is very easy for someone without access to mentoring from a friend or from a guildmate to miss a piece of that learning (if they're good enough at other things they will just soldier through, maybe looking a little less skilled to those around them) (if they don't have enough other skill, they may decide FF is too hard and give up). NN was created as a safe place (beyond friends or guild) for people to get questions answered, help, and maybe even mentoring on their journey through that learning curve. These toxic behaviors negate the basic purpose of NN.
1) Elite Players? To be honest, I've stopped using the term 'elite' since a lot of people love to label raiders as such if they are outside of doing Extremes or even raids on Normal Mode. Let's also be fair: After the Expansion launch and you reach the end-game, you have to think on what you're going to do next; some people have already gotten everything to 80, so they strive for harder things. There really isn't much else after you complete the story until NG+ arrives in 5.1.
2) If they're being outspoken against new players for not doing as well as Mentors, then it serves for them to be reported for harassment, since this does not follow what a Mentor is supposed to be if the harassment is extensive.
3) I myself answer this in regards to end-game sometimes, but what most people assume is that they're 80 already if they're asking about rotation; on the other hand though, it falls to the Mentor to be thorough in regards to helping another learn.