grammar - What is wrong with the expression 'most perfect', and the adjective-forms 'rounder' and 'squarer'?

Here is an excerpt from the textbook High School English Grammar & Composition, by Wren & Martin (2005 edition by S. Chand, New Delhi):

Certain adjectives do not really admit of comparison because their

meaning is already superlative; as,

Unique, Ideal, Perfect, Complete, Universal, Entire, Extreme, Chief, Square, Round

Do not therefore say:

Most Unique, quite unique, chiefest, extremest

But we still say, for instance:

This is the most perfect specimen I have seen.

My questions:

1. Isn't the last example contradicting (by using most perfect) what they described above? What are they trying to imply here? What should I take away from it?




2. I have heard the expression 'quite unique' at-least in informal English. Is it incorrect in formal English?




3. I have seen the words 'squarer', 'squarest' and 'rounder',
   'roundest' in the dictionary. So what's wrong with using them?

   
   
   
   

   Suppose a child tries to draw a circle and it doesn't turn out to be
   a perfect circle, so they make another attempt and the circle they
   draw this time is better than the one they drew before; so you tell
   them that this one is rounder.

Answer

If we take square as the example, if it has four equal-length sides and 90 degree corners, it is a square. If it doesn't have those, it isn't a square, so there is nothing between the states of square/not square to be graded. Similary, something is either round or it isn't round, perfect or imperfect, unique or not unique, etc.

The confusion arises because in normal, informal usage comparatives like squarer or rounder are used in the sense of "closer to being square/round" simply because it is by far the easiest way to describe that situation.