There are ways to get such boundaries without having separate microservices. Also having dev teams across time zones is itself a challenge. The devs are cheap

There are ways to get such boundaries without having separate microservices. Also having dev teams across time zones is itself a challenge. The devs are cheaper, but integration is worse. In Steve McConnell's book Software Estimation the industry average seems to be that development is over 40% longer, and defect rates also go up. That, however, is a debate for another day.