Dogfooding works when affected employees have the ability to improve the product.
You wouldn't want to eat dog food that wasn't prepared in sanitary conditions, so if you worked at a dog food plant and knew you'd be eating something that closed through that dirty grate, you'd clean it. You wouldn't want a program on your PC that regularly consumes an entire core while idle or that crashes when active, so you'd fix those issues if it was your software.
People naturally want to fix problems that affect them and add features that would improve their daily use of a product. At a small company or startup, where people can do this, you should use your own products as much as possible.
But if you are a Microsoft/GitHub employee with no access to the Teams code, not even access to a human being who works on Teams, there's no point. Use whatever meeting software lets you do your job best.