I feel as if that can rephrased "Don't do it because it is not done." A left-hand side constant is a convention that can have practical benefits in limited cases. Which at least should merit consideration.
"Don't do it because it is not done" is a good reason unless you're working solo and are sure your code will never be seen by others. And even then, it's a good idea to stick to what's done so you don't accumulate bad habits for projects that do have others looking at the code.
