SO for Teams has many of the features of the main, public Stack Overflow site. As such, it is a great Q&A site. We use it is parallel with MS Teams and with email. It is used for more permanent and easily searchable knowledge repository. We also have a wiki, and other knowledge repositories. Stack Overflow for Teams is a big part of the overall process of getting your question answered by other people, and also reusing this answer by others who have a similar question.

Stack Overflow for Teams saves countless hours by eliminating the need for lengthy calls/meetings.

It is instrumental in increasing developer productivity and enabling a forum where I can go ahead and post about anything I need answers to.