Microservices solve a number of engineers scale problem, not a traffic scale problem. Tech scale is drastically more simple in a single application, because you don’t introduce an unreliable network and related complexity into all of your problems
Interesting, in my experience we've never had major issues with our service mesh or internal networking. It definitely introduces a lot more complexities. I suppose we've always had a dedicated devops team so I'm probably unaware of a lot of these issues.
I'd be interested in some resources around this topic if you know of any.
I'll be honest - pretty hard to find objective literature on it, because most of the literature is just trying to tell you microservices will solve all of your problems. I think ultimately the best link between the two is Amazon's move to microservices and their focus on "2 pizza teams".