Answer:
Even if you make a drawing to scale, it would be difficult to determine the exact precision that is needed.
It would be time consuming to measure each of the lines to determine measurement.
The basis for modern part dimensioning is the need for interchangeable parts (being able to buy something off the shelf that fits what you already have)
Step-by-step explanation
When dimensioning, it is good technique to avoid listing the dimension more than once through out the drawing.
If you need to list a dimension more than once, for accuracy or ease of viewing, you must encase the dimension within a set of brackets.