Because you are not charging $3000
The outstanding balance has nothing to do with it.

example;

Your Take home Pay is $1,200 per month

for the last 12 months you Have charged $3,000 each month
In each of those 12 months you Have paid the Minimum Payment. Roughly Interest +10% of the outstanding balance

So Next month You promice to only Charge $1,500.
Of course you will still Make the Minimum Payument

Presto You have cut your deficit in Half.
and your credit rating is still in tact.

Paul