Isn't this (kinda) true, in general?

I work at Google. Many of the "official descriptions" of various levels include "size of team" as part of the description. I think, generally, anyone in a middle management position, particularly at a growing company knows that "more people equals more advancement".

Yeah. At many places, team size (and eventually, number of teams you manage through other managers) is codified in manager role descriptions.

Headcount based promos is the most backwards system out there.

But Amazon is too dysfunctional to change.

It can make sense when done right. If the team grows organically in response to the work, rather than work increasing to grow the team, it can make sense to reorg the team and often internal promotions can make that transition more smooth.

Goodharts Law: “When a measure becomes a target, it ceases to be a good measure.”

what kind of asshole makes head count a promotion statistic? What does this prove?

Once organizations get to a sufficient size, increasing your "scope" is the only metric left to compare. You could compare revenue, but the easiest way to get more revenue is to increase the amount of work that falls under your purview. You could compare profitability, but then you encourage everyone to make the most expensive products they can get away with and your company fails. You could compare productivity, but there is no scientific way to do that, and funding the research required would bankrupt you and your company fails. You could do it by vibes, but the snake oil salesman will sell you garbage and your company fails. You could do it by seniority, but then you stagnate and your company fails. You could do it at random, but then none of your managers would bother trying and your company fails.

Do feel free to suggest a better way to compare two managers that doesn't fall into worse situations than "scope".

So, there is no objective way to measure performance of a manager ? It sounds similar to measuring the productivity of developer.

Measuring scope to evaluate performance is like saying developer who works on most number of tickets/bugs is the highest performer.

We know that's not true and we also know how it can and will be fudged(w.r.t managers its increasing un-necessary headcount).

If we are able to come up with a solution for developers it shouldn't be too difficult for managers too.

How would profitability fail the company? Too expensive products won't be bought means no profit, but if you can get away with the price, you're not failing, are you?

See Google, they keep cancelling and abandoning products that aren't immediately profitable enough.

BS, you can measure management productivity and effectiveness.

Lazy management, ones that focus on "metrics" and "numbers" rather than actual engagement with their teams/business lines.

I'm only 20% joking here...

Goodheart's law. As well as too many cooks.

it's not like FAANGs are strapped for teams. Managers can just mnage horizontally instead of needing to hire more people to "prove themselves" (especially when the hiring process is absurd these days).

I thought this went out when the USSR fell?

This is a common issue in large corporations.