Let's start with an example. Boxing is often scored after the 10-point-must-system. 

> The most widely used scoring system since the mid-twentieth century is
> the "10-point must system", so named because a judge "must" award ten
> points to at least one fighter each round (before deductions for
> fouls). Most rounds are scored 10-9, with 10 points for the fighter
> who won the round, and 9 points for the fighter the judge believes
> lost the round. If a round is judged to be even, it is scored 10-10.
> For each knockdown in a round, the judge deducts an additional point
> from the fighter knocked down, resulting in a 10-8 score if there is
> one knockdown or a 10-7 score if there are two knockdowns. If the
> referee instructs the judges to deduct a point for a foul, this
> deduction is applied after the preliminary computation. So, if a
> fighter wins a round, but is penalized for a foul, the score changes
> from 10-9 to 9-9. If that same fighter scored a knockdown in the
> round, the score would change from 10-8 in his favor to 9-8.,

As long as I don't miss something it would be exactly the same with just smaller numbers. You would get the same results with for example 3, 2, 1, 0. Boxer A wins two rounds with 10, looses a round with 9 and one with 8. Boxer B looses two times with 8 and wins two times with 10 accordingly. 
It doesn't really matter if Boxer A wins with 37 (10 + 10 + 9 + 8) or 9 (3 + 3 + 2 + 1) since Boxer B has either 36 (8 + 8 + 10 + 10) or 8 (1 + 1 + 3 + 3). 

The most widely used scoring system since the mid-twentieth century is the "3-point must system", so named because a judge "must" award three points to at least one fighter each round (before deductions for fouls). Most rounds are scored 3-2, with 3 points for the fighter who won the round, and 2 points for the fighter the judge believes lost the round. If a round is judged to be even, it is scored 3-3. (...)

This is just an example. I know at least archery* which has a similar "problem". Why do we have such systems? I mean it just increases the numbers but adds no value to the scoreboards. 


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*) In 3D archery a scoring system like this exists: 

1. Arrow bulls-eye 20, target 16
2. Arrow bulls-eye 14, target 10
3. Arrow bulls-eye 8, target 4

A scoring like

1. Arrow bulls-eye 10, target 8
2. Arrow bulls-eye 7, target 5
3. Arrow bulls-eye 4, target 2

Would create exactly the same result.