Is there such a thing as constructive criticism? Or is all criticism just an overwhelming need to parade one's superior discernment?

I'm leaning toward no, I don't think there is anything constructive in any criticism. I can say, no, this doesn't work for me, and then that gives you the freedom to look elsewhere for applause and/or companionship. If I want to take the time I can show you alternative ways. Aside from that, I believe in the freedom, and the responsibility, of your soul forging its own way among the myriad possibilities.