Unfortunate approach.

My company not only encourage transitions, we actually "pay" for them. That means we will assign a senior developer that will have responsibility for growth of the new mentee and we purchase any educational materials the person requires.

We have quite decent amount of transitions within last few years and all were successful. They do require commitment and investment from both sides.

I do believe we are stronger for it as people appreciate the opportunity for growth and support we provide. We, on the other hand, re-gain skilled colleague that is not looking elsewhere.