Pretty much microservices happened because of managers. Managers are promoted to high level jobs such as Director or VP based on number of direct reports. This won't happen with a small team of devs. So they need an infrastructure team, a devops team, a SRE team, a QA team, a microservices core team, an access management team, network engineering team, AWS integration team, and the list goes on. What was once a four person team is now a 50 person team costing 10 million per year, but, hey, the guy/girl gets his VP promotion for setting all this up.