My understanding is that they bundled it in so conveniently that it’s somewhat of a default. They probably don’t have to care because the average company isn’t about to do an entire slack deployment and integration into their purely MS ecosystem
accurate, I work for a company that uses a bunch of Microsoft products. it’s apparently a good deal from a financial perspective and is popular in the public sector because of the easy integration for non-technical users. alas, you get what you pay for.