Conway's Law for infrastructure / tooling, perhaps.

If you have complete control over the organisation's dev process, and are willing to invest enough, you can build something better than the default free / distributed / popular tooling.

This is probably partly enabled by the fact that they don't have to care about trading patches easily with the outside world. Then, by rolling their own in-house workflow/infrastructure/tooling, they make it harder for outsiders to contribute, even if this were organisationally possible and desirable.

Based on some brief experience at Oracle, accepting outside contributions is a legal nightmare - it is frequently less expensive to do a clean-room re-implementation of a feature than go through the lawyers and contract negotiations now and in the future to get code ownership rights worked out.

agree with this. I think monolithic repos are part of legal strategy in enterprise.

That's because it's Oracle. Everything associated with Oracle is a legal nightmare.

I see similiar issues at mozilla.

Monorepos are far easier to work with from an engineering standpoint, for external contributors they are definitely prohibitive.