Completely flawed eh?
Yet you give a perfect example, Jo bloggs youngest capt no longer is trapped in said airline, they leave as soon as they choose to leave and live in another country or get more money or fly a different shiny jet, grow up get a wife/husband kids change lifestyle whatever floats their boat. Said airline gets sick to death of training pilots and finally improves their COS to put some stability into their flight crew and perhaps hire crew from another airline and so conditions stabilise like jobs in the rest of world where highly skilled staff with long time experience credentials can control their 40 year career.