Lancer is surprised by his students question, not angered.
I see, I will explain to you why.
I'm taking RP portion out of this to answer the question properly.
Description is everything especially in the RP today. Though you are right most of the time people don't describe much their performance for the technique, in the RP mostly what happens is people perform it and explains how. To an extent you are right and in my training you will soon get to that portion where you learn about it more then you actually perform it. To be honest performance will be taken out of the equation. The main purpose is to gain the habit to be descriptive and proper for when you get to the more complicated stuff you won't be overwhelmed. We can easily go to the tough stuff but I already know how that will end, if you can describe simple jutsus now how can you even talk about their main purpose? We are taught to walk before we run, right? I want to take it one step at a time so I can expect the best out of you. Also for senseis that don't describe jutsus as much, I question you this? Who are they fighting?
Here is the thing if two senseis or two very powerful ninjas fight each other then they barely need to write,Why? They already know how to perform each and every jutsu to an extreme extent. They don't need to add to much because well they already know the jutsu to its absolute limit.
Now I'm going to be going into a little bit of a rant. In today's RP especially in this Generation their is far to much complaint and annoyance. How do they start? By misusing, not understand, and not being as descriptive as possible. I understand in spars your less caring but in a official battle description is key some of the best RPers today are brilliant at description when they have to be.(Sharingdork, NK, Madara, Scorps) Though new RPers or less deserving just are to lazy to write a sentence or two more that confusion rises and arguments take place. I do not want neither like it, its a pet peeve of mine. So whenever I battle even if a spar I try to be as descriptive and good as possible so my opponent knows full well what I'm trying to do and arguments do not rise. Its not fun arguing and you just look stupid. Have fun with it and try not to be lazy.
So in short I teach you to describe almost as a warm-up to get you in the habit and enjoy to write. When I feel you are adequate enough we will talk and get much more in the thick of things with the jutsus. I only ask the best for you, I know how it is to be handicapped in the RP I want to be the pillar that helps you become a great RPer. I hope I answered the questions and explained myself the best I possible can.