Junior teachers are often more easily pushed around, while senior teachers can have the experience and connections needed to push back against bad administration.
Letting administrators determine who the "best" teachers are can mean that administrators will pick the most obedient, not the most effective. A seniority system has obvious flaws, but I don't see increased bureaucratic power as much of an improvement.
This is going to be true for any group of professionals. Doctors, lawyers, software developers. Junior ones will do what they are told. Senior ones will push back and say "this is stupid" when management tries stupid rules.
Yet the senior professionals in those fields are valued. I suspect because their employer cares if the organization does a good job. I've seen school administrators range from mildly concerned to completely unconcerned. As long as the bosses' jobs aren't in danger, they don't care, and their jobs tend to only be in danger when something goes really really wrong, like a school shooting. So, like any other bureaucracy, they work hard to clamp down on anything out of the ordinary.
I think school choice is important for getting administrators to care. Of course, if parents pull their kids out of school A and into school B, and some higher power (like a district) simply moves administrators over from A to B, nothing has been accomplished.
Junior teachers are often more easily pushed around, while senior teachers can have the experience and connections needed to push back against bad administration.
Letting administrators determine who the "best" teachers are can mean that administrators will pick the most obedient, not the most effective. A seniority system has obvious flaws, but I don't see increased bureaucratic power as much of an improvement.