Out of necessity? I know we live in times when elites seem secure. But it wasn't always so and it won't be always so.
It is so right now only because of how good modern common people have. But it's going away now. And if security of elites depend of well being of others it's sort of self-regulating system albeit way too slowly.
There's also pressure from the other side. The longer living elites means it will get crowded at the top, so elites might be open to some means of culling their numbers.
Mechanism that could be applied way earlier than old ossified out of touch rulers die now. And applied more merit based.