Can add Visual Studio to the Office/DirectX/Outlook/ActiveDirectory section.
They're sort of heading in this direction with VSCode. I can imagine that VS itself is a non-portable COM-infested disaster area.
Just like a C interface is a small and nice abstraction over plain registers/stack call models of the past.
The advent of calling conventions like C was a huge step forward in 1970s. Before that, there was a mad zoo of passing parameters via random CPU registers and praying that you made no mistake and it would work without a crash.
COM is no different. IUnknown is just 3 methods (QueryInterface, AddRef, RemoveRef) over a plain C. It immediately brings an ability to use service model design in APIs.