Someone will probably reply with more detail but the gist of it is, it's true. I know a guy who was hired with very, very, very little flight time and worked his way from the 707 FE spot to right seat to captain to L1011 captain to spending the last ~15 years in the left seat of the 747.

Funny thing is, he went to school for a totally non-aviation subject and no specific goal, and got a job for TWA throwing bags and that sparked his curiosity.