Yusef Lateef plays both oboe and bassoon. I also saw him play the Dulciana at a session in '05. It is not the kind of music we discuss on this board but he is a giant in the jazz world..
I cannot imagine an oboist/bassoonist being a giant in the jazz world. I am not that big of a jazz fan, but I have never heard of him before. Perhaps he is a giant in your part of the world, but not here so much.
I would agree that any instrument is irreplaceable in the orchestra (even the triangle has its importance).
Well, there is no "triangle player", but rather a percussionist that plays everything in that section (or multiple percussionists). Actually, percussionists have very virtuosic parts in some pieces (either as a timpanist or otherwise), so percussionists have come into their own as of late in the orchestral world, and there are quite a few percussionists who are virtuosos.