You can have both tiny repositories which do a single thing and large repositories that consist of many projects. It's totally cool to have both, assuming your team can be trusted to make the appropriate choices as they create new projects.
> And then people forget how to make distributed repos work and claim things like "omg I have to make 1 PR per repo when making breaking changes!", as if it was a big deal or it wasn't a solved problem.
Is this a solved problem? I typically do make one PR per repo to resolve breaking changes, though it's certainly not a big deal. Still, if there's an easier way, I'd love to hear about it!