Nah. CFI to airline wasn't the most common path. CFI and then ANOTHER job or two, and then to the airlines, was the common path. Few were getting the 500-1000 hrs multi time the airlines often required. So it was often CFI, Part 135 air taxi, cancelled checks, fly by night cargo operator, sit right seat 'don't touch anything' charter or Part 91 operation. Even in the 1980's the most common civilian path was via regionals airlines with night freight or checks in a light MEL another common feeder path. I don't recall, but it might have happened, for someone in the last 39.5 years to say "I got here from a CFI job." Back in the 1960's, when the Vietnam War pilot shortage hit, the majors were hiring some pure civilian CFI's. One of those was a 727 FE who got his 727 FO award about 5-6 years later. His peers were kinda of chuckling, as much as a 14 yr old kid could understand - "he's in for a surprise when he gets in the sim." Can you imagine being a 1000 hr CFI and 5-6 years later, with little of no flying in the meantime, getting a 727 FO award? LOL.