You want managers to have more turnover than seems to naturally happen, they'll respond by hiring under-qualified people they can fire and over-qualified people who will move on. It's really a no-brainier solution that any manager who's team isn't meeting the criteria to check the box can implement in order to check the box.
On that note, I wonder how these forces might work to fix ideal team size to align with these flawed incentives.
Most I ever had was 8. When it got larger than that I had people step up to active leadership roles. Eventually they did the same.
In a tech workplace 20 is probably a real handful.
My first true corporate experience was with big-four Deloitte. The culture there is "up or out". May sound sketchy to outsiders but it was actually a really supportive environment.
I already feel very uncomfortable if I'm "the dumbest person in the room". Equally, I don't want to be the smartest.
He decided his team was good enough so he submitted the paperwork for 15% for everyone. It worked, he never heard back and everyone got their raise. This went on for years.
Then one day I'm in a meeting with a bunch of management and some small talk comes up about the set raises. My manager notes he doesn't follow the 'guidance' and all the other managers gasp.
For years these guys just did what they thought was expected, didn't even try anything different.
The managers at that company were more drones than anyone else... needless to say eventually all innovation slowed and the company feel into process hell.
Outside of regulatory or compliance requirements, in many cases, "policies" are simply suggestions which can be ignored.
I had a great manager at my last company. Very good people person, would read on his own time to try and improve himself, etc. He had also been in our department the longest - upper management was always coming and going every 2-3 years. I asked him one time why he didn't want to go for one of those higher level positions and would rather stay at this sort of stressful one after a decade. He said he didn't want to deal with all the headaches at that level (more meetings with C-level people). He just wanted to keep his head down, take care of his team, and go home (a 1-2 hr commute each way).
Given the precarity of much existence in the US, and the ability to be fired on a whim, it's no wonder the 'drone' mentality, of not bucking the system, is pretty normal. Suck up the BS until you can retire. I guess at least these days most of us don't have to deal with hot tar.
It's not a very realistic risk for most people.