One problem is when you get hired at 500 hours, and they pair you with a Captain that upgraded two months ago at 1500 hours, and you learn everything about being an airline pilot from this new Captain who barely has enough experience to hold an ATP.

A year later you have 1500 hours and a wet ATP and you move to the left seat with the same experience (or lack thereof) that your first Captain had. But now you're the professional example for some 500 hour wonder. You have a grand total of one year of 121 time between you, and neither of you has shot an approach in icing.

I don't know if 1500 is the right number, but I can figure out it's three times more than 500.