If a team of 6 developers created 15 microservices, I'm afraid that they don't understand the pros nor the cons of microservices and they should be fired instantly.
Are you suggesting that the number of developers does not place a maximum cap on the complexity of your infrastructure?
Because if what you are saying is that nobody should ever get near that cap, so it should be theoretical only, that still supports a correlation.
Because infrastructure complexity <> Software development complexity.
I'd also note that the OP had no concept of time in it - it didn't include a timeframe, so we aren't capped by developer man/work-hours.
If we are talking instantaneous support, there is no telling how this correlates - one complex microservice may be too complex for many devs, or many microservices simple enough o be supported by just one.
If we are talking about about either development hours, or code-familiarity, then I'm not sure how we are capped - are we going to limit the number of LoC a dev can write, repos they commit too etc, as well?
Oh, ok. Point taken. This alone invalidates everything I wrote.