I assume there must be people reading these forums who are interested more in clarity than in proper Unix terminology. So long as they know the difference.
A very important aspect of clarity is accuracy. If you tell a user to look for something in
library > app support they'll come back and say they can't find it. When they do, it'll be your fault, because you gave them inaccurate information. Inaccurate is
ipso facto unclear.
If I tell them to look in
~/Library/"Application Support", they may still not find it, but at least they won't have to autocorrect my input as well as their understanding. They won't have to wonder whether "app support" is supposed to be "Application Support" but you decided to save yourself a few keystrokes, thinking that it's so clear in your mind what you meant that it must be clear in their mind as well.
The fewer parts of your message they have to guess the meaning of, the better the odds of a successful communication. Don't expect your reader to read your mind. All they can read are the words you write. Write what you mean. As the saying goes: if you can't say what you mean, then you can't mean what you say.
