One of the things that medical students do is learn to “argue” or discourse about cases and patients. Doctors learn that verbal discussion and disagreement (point/counterpoint) is not only important but useful. A closed system in which argument is forbidden is always deadly. We see this in countries where freedoms are curtailed, and in our own country where, in the past, some books have been burned because they were not acceptable to “certain people”. A free system is MESSY, but necessary, if true freedom is to exist.
In academia, however, and in associations of teachers who are unaffiliated with an academic organization, arguing over anything is considered “awful”. No one speaks up about any issue lest that protest seem “unprofessional”, “disrespectful” or “disruptive”. How unfortunate.
If I disagree with you, even very strongly disagree, and let you know that I do, it is because I trust you, not because you are my enemy. I don’t believe in enemies. I am not paranoid. If you can point out to me in an argument that I am wrong, and supply me with rational reasons and judgment about why, I will change my mind. I have done so in the past many times. If you do not speak up, I might never know that I could have done a better job, and that would be bad for me and for my students. I have argued with some pretty high-ranking pedagogues and scientists then gone on immediately after to laugh, relax and have a nice dinner or lunch, with neither of us the worse off for the “head banging”.
I have colleagues who loathe that I am forthright and in being so I sometimes upset others, most particularly them. They wish to prevent me from “doing battle” with “the enemy”. They don’t want me to upset anyone ever. They see things in black and white – the “either you are with me or against me” mentality. Too bad.
I am well aware that there are others who will be condescending and insulting to me as part of their desire to make me or what I say wrong. I have a right, as does anyone, to stand my ground, not back down, and support my own views, and I steadfastly refuse to allow someone else to cast aspersions  on me personally for my professional beliefs. Hopefully, in telling the truth as I see it, I am making room for them to do the same, without calling me names.
Teachers of singing need to get out of the “Diva Mindset” where all argument is seen as a kind of war. Nothing could be further from the truth, and seeing enemies where there have never been any is a mistake in perception that makes it harder to get to honest communication.