Requiring everyone to talk to everyone so everyone has global context isn't just "devs don't want to talk to each other"; it is actually an information dissemination and coordination problem which scales non-linearly (at least n^2), and needs some kind of modularity to be tractable to normal humans.

Microservices are like modules but for SaaS rather than shrinkwrap, and are where you end up when you follow SLAs, encapsulation of resource consumption, etc. to their logical conclusion.