My experience is it adds a multiplier 10x to the work that needs to be done, which is then a good fit for the 9x extra developers upper management decided to hire.

Sure, it keeps everyone busy with work they feel is meaningful -- but it really is work that was not really needed in the first place with a monolith.

Much simpler to try to stay fewer developers as long as possible.

Also in my experience it is impossible to get people along with organizing the company along software architecture division lines, thus creating a lot of political problems.