[joshuamorton]

Amusingly I agree with your conclusion that we should discourage breaking API changes, but conclude that monorepos are therefore superior.

Making the team causing the change have to take on the work of migrating clients means that they will make the change as small as possible, and undertake work to to minimize the scope of the change (and make it as backwards compatible as possible).

The alternative is a team publishing a v2.0 API with many incompatibilities and throwing it over the wall, without care that anyone else uses it, and teams eventually needing to migrate to a wholly new API for the one new feature they care about. Or in other words, someone is going to build a compatibility layer, it's more efficient for the owning team to do that, and monorepos encourage that kind of approach.