Sometimes standoff is pointless. Friendlies on the ground are in a knife feet with the enemy less than 100m away and they need air support. Now close, and slower to better maintain SA on who the friendlies are and who the enemy is -- and the ability to deliver weapons with lower Risk Estimate Distances and/or Collateral Damage Estimates is critically important. The GAU-8 does both. The F-16 gun is useless. A laser guide bomb in this scenario may present too much risk for fratricide.

A-10s can carry more ordnance, for a longer time over a target area, and need less tanker support to do so, than an F-16. And for less $/flying hour. It does cost speed. A-10s don't go anywhere quickly. But it can perform CAS in a standoff roll, or in a close-in fight equally well.

Here's a simplistic example. If the enemy isn't aware that your side has CAS, he may believe that it's a good idea to attack your side in a certain way. He may get killed in the process, but that attack may result in some losses on your side.

If, on the other hand, the enemy is made aware of your CAS, he may opt to play it safe and not risk his assets by attacking you that way.

It's like when you play chess: some pieces control some areas of the board without doing anything. Just by being where they are, they restrict the opponent's actions.