I work for a startup which recently hit the "100 employees" mark. We have brought in senior managers from other companies, including competitors. These new people are introducing more structure (and it's probably a good thing), but they are also creating new management roles which are being filled with their old colleagues. This is happening at all levels, from C-execs hiring VPs who reported to them in the past, to engineering team leaders hiring their old team.
In all of this, staff who worked at this startup for many years is not getting promoted or given more responsibilities. In fact, 90% of our engineers left or were pushed out.
I understand that this is good for the senior managers, e.g. "I have a target to reach, I feel more confident with people I already know". But, the startup is losing most of its previous staff, from engineers to executives.
So, my question is:
Is this process an integral part of how startups develop (new senior management replacing staff and giving promotions to old colleagues)? And if this is the case, how should one plan a career in a startup, if there is a deadline when your work will help bring somebody who'll replace you?
Note: I am not looking for an ad-hoc answer, I want to know if this is EXPECTED and COMMON for any growing technology startup.