You mean to say before the 1990s the A10s didn't face SA-6/7/8/9/13 etc plus Shilka's, Tunguska? Or that those were no good (many still in use today). Plus, you realize the A-10 was used in combat for the first time during the Gulf War in 1991? It destroyed more than 900 Iraqi tanks, 2,000 other military vehicles and 1,200 artillery pieces, making it by far the most effective aircraft of that war ... moved on Bosnia-Herzegowina 1994-5, Serbia 1995 and 1999. A-10s did not take part in the initial stages of US going in to Afghanistan in 2001 but flew there from 2002 on. The US attack on Iraq that began on 20 March 2003 involved sixty OA-10/A-10 aircraft in the early combat there. Total combat losses ... some 7 in Desert Storm, 1 in Iraqi Freedom ( = shot down in combat or lost as a result of combat inflicted damage.)
Why USAF hates A-10 and why it can’t be replaced « Defense Issues
Thanks, I wanted to write a comprehensive response for @forcetrip, but I see that you have already answered him with a more solid response. BTW, the article that you posted is also very interesting. I believe that it is not logical to retire a very cheap and extremely useful attacker in favor of bunch of money-hungry n-th generation fighters. each goal in the battle field needs to be achieved by the military equipment that is exactly designed for the mission. Instead, I suggest to start a new project to build an attacker which upgrades A-10 to a new cheap, and CAS capable aircraft.