If the version numbers of all services built from the PR are identical, you at least have a pretty clear trail to figuring out WTF happened.

Even with a few services, we saw some pretty crunchy issues with people not understanding that service A had version 1.3.1234 of a module and Service B had version 1.3.1245 and that was enough skew to cause problems.

Distinct repos tend to have distinct builds, and sooner or later one of the ten you're building will glitch out and have to be run twice, or the trigger will fail and it won't build at all until the subsequent merge, and having numbers that are close results in a false sense of confidence.