You have raised the discussion on employee exit or employee attrition. You have raised the validity of the reason of exit of juniors on account of bad bosses but what about the bad behaviour of the juniors?
Well, gentleman, it is not a question of juniors and seniors but of the organisation. Everybody works for the organisation and organisation's interest have to be given primacy. Against this backdrop, seniors have more responsibility in protecting the interests of the organisation as they have authority.
However, exercising of the authority should not be arbitrary. They should keep in mind that their wrong decision or action could destroy the motivation level of the juniors. Over a period of time, this demotivation converts into frustration and which in turn results into employee quitting the company.
Juniors get frustrated with their bosses when they find that their bosses lack impartial attitude. Secondly, their technical or functional expertise also matters.
Many times, managers get the promotion because of their length of service and not necessarily because of their level of knowledge or managerial qualities.