Maybe look up the game credits, I sometimes do and I often see like 10 UI programmers (in games with a ton to 2d UI), 5 gameplay programmers, 5 environment scripting, etc. Sure it is not small amount of people, but it is not an army.

Also those programmers seem to be neatly segregated in different areas of the project which I imagine work similarly to boundaries between the microservices at keeping the logic isolated between teams.

: I do AM surprised just how much QA people are credited in games, QA for major games sure do feel like an army.