Worth checking the actual requirements: the A-10 was driven by thre 1966 directive that “the Air Force should take immediate and positive steps to obtain a specialized close air support aircraft, simpler and cheaper than the A-7, and with equal or better characteristics than the A-1″ (Report, U.S. Congress, House, Close Air Support, 89th Congress, 1 February 1966.)

“the intended operating scenarios stressed a permissive environment”

“The design mission for the proposal consisted of: 5 minute warm-up and take-off; climb to 5000 ft at optimum power setting; cruise to 200 NM at 250 knots; loiter for 2 hours at 5000 ft; descent to sea level for 15 minutes of combat at 250-300 knots; climb to 5000 ft at optimum power setting; cruise back to base at 5000 ft, 250 knots; descent and landing with reserve fuel for 20 minutes loiter at sea level.”

Ask the Israelis what happens if you loiter at 5000 feet within twenty miles of a Soviet-styled armoured formation in 1973… the A-10 mission didn’t look much like “take on the Soviet hordes”.

“The A-X fared well in a force mix analysis for conflicts where air superiority was not necessary, but for a high intensity conventional war (e.g., the envisioned war in Europe) the demand for air superiority/interdiction was considered critical, making it difficult to justify reducing the numbers of multi-role aircraft in favor of A-X acquisition.” (Director of Defense Research and Engineering (DDR&E) Development Concept Paper, DCP-23A, completed December 1969)

“As the threat focus changed to the European Battlefield [my emphasis] some of the earlier considerations were being looked at again.” - this was after service entry. (David R. Jacques, PhD, LtCol USAF (Ret) and Dennis D. Strouble, PhD; “A-10 Thunderbolt II (Warthog) Systems Engineering Case Study”, 2010 Air Force Center for Systems Engineering.)

“The Air Force always believed that a fast multi-role fighter was a better choice for the feared war in Europe, but agreed to procure the A-10 for contingencies and “limited wars” like Vietnam.” (ibid.)