This sounds like you've been at minority-shareholder-operated companies (as opposed to owner or majority-shareholder operated). They are managerialized and the

This sounds like you've been at minority-shareholder-operated companies (as opposed to owner or majority-shareholder operated). They are managerialized and the reason job-hoppers are negative is that it is a bureaucratic organization with multiple competing power centers. Things get done based on favors and insider relationships, as opposed to a clear authority. Since it takes a while to build up a "balance" of favors to call upon, it takes a long time to be productive. That's the real reason. #1 is a direct consequence of this structure, #2 is a side consequence. There's no good reason you couldn't hire senior people from outside - the only reason to favor promoting from within so heavily is that they have decrypted the power factions while they were "cheaper" junior employees. #3 just sounds like an exception situation - if you were actually tasked to "staff up a full team" - you would no longer consider job-hoppers, for all the previous reasons.