I'd risk a guess: because salary. Some companies may afford paying more and some may not (because of their current growth stage, market they operate on etc). Ev

I'd risk a guess: because salary. Some companies may afford paying more and some may not (because of their current growth stage, market they operate on etc). Even if some of them manage to get past the early stages, employee rotation is something worth thinking about. On the other hand, in most or all of the companies I've been somehow related with, more experienced developers have naturally invested their time in helping juniors learn.