If you want someone to learn new skills don't be an idiot by not healing them. Take the time to write one line what they could do to be more efficient.

Let's be real here: we all suck at some point.
I for one would still be just TERRIBLE if one guy in df hadn't wrote "use defiance more".
That's all. No ragequitting nor insults just a tiny bit of help that allowed us to make it through.

Same in XI. It's the other players that taught me how to play. Deaths not so much.

Be civil. It's not that hard.