I don't agree with this. If you can show clearly what you mean in short words, then don't use lengthy words.
How often would you be able to express your thoughts in a one line reply,yes definitely you cannot always express yourself in long or moderate replies,but definitely if your post history is filled with one line replies then it just goes to show you're not contributing to the community
Most times one needs to expantiate on their thoughts and shed more light on it,its impossible to do so in just one Line,that's not to say every long reply makes much sense,it all matters on the content of what is being said