In “The Beginning of Infinity,” physicist David Deutsch makes a point like this about styles of government. Deutsch suggests the defining characteristic of a good governmental system should not be whether it consistently produces good policies, but instead that there is an extremely low-cost barrier to removing bad policies once it becomes clear they are bad.

Thinking this way, if monorepos permit a situation where there are monopolicies about allowed languages, allowed deployment tooling, etc., and those policies cannot be quickly discarded when it becomes clear they are bad for a certain business goal, then this is perfectly good reason to disfavor monorepos regardless of whether they cause the bad policies.

I think your responses continue to miss the point because you’re talking about correlation and causation as if it matters in a situation like this: but it precisely doesn’t matter.

If a tool doesn’t actively prevent certain policy failure modes (even if it does not cause anyone to choose a bad policy), that is a relative failure of the tool.

Contrasting with polyrepos where it is quite harder to enforce failed monopolicy ideas is one area where polyrepos are a better tool: to misuse polyrepos policy-wise you have to go way out of your way and add a lot of draconian policy enforcement tooling that often can still be circumvented. Those inherent barriers are a good thing that monorepos don’t have.

Separately, I’d also say that the political failure mode where central IT wants to enforce draconian policies is extremely common, and those types of organizations specifically see a monorepo as a tool of (their desired) oppression and control.

Since the base rate of occurrence of horrible companies is super high among all companies, it probably does mean that P(bad | monorepo) is pretty high conditional evidence of a bad workplace culture.