Not max out. But like - say I'm planning a trip to Hawaii. I might want to open the Hawaiian Airlines credit card. Spend the 1k in like first 3 months to get X amount of free miles. If a person has too much credit, the new card will say - they have too much credit and need to close some.
Edit - wait read yours wrong. Yea CC company fear of too much open and going into too much debt they don't get paid.