What pedagogical purpose does this serve? I'm a fan of tough love from teachers. I'd rather get a low grade and learn a great deal than a high grade and learn nothing. For some instructors, part of that is being willing to say the equivalent of "this is complete shit" when your work is, in fact good, but not up to standards.

But the best ones do it in private, or in written feedback, or generally to everyone as a motivational tactic. All of that I'm willing to tolerate, and I've seen some (not many) user acerbic brutal feedback to achieve results out of me I'd never find possible.

But never have I seen a teacher signal out particular students, compare their work openly, while holding up other particular students as examples of what not to do.

Is that good or bad? The principle of rewarding individual excellence is good, and the attitude could even be forgiven in certain circumstances.

But there's a way to do that without being a dick. And if you're going to be a dick, you better b the extremely rare person that knows how to be a dick properly and effectively, usually with an undercurrent of good humor and in the pursuit of ultra-high standards.