As is stated or illustrated in many different articles, including this one, rotating black holes are oblate spheroids. It is likewise stated in some sites that this fact should be intuitive, as all rotating bodies are oblate spheroids. However, this is 1) not true, as objects which are perfectly inelastic will retain their original shape when spun, and 2) as far as I understand, planets and most other bodies gain this shape because of hydrostatic pressure, which obviously cannot apply to light and, again in my understanding, does not even exist in a black hole.
My question, then, is: why are rotating black holes not perfect spheres? Isn't gravity uniform in all directions? Or does the rotation of the black hole disrupt this uniformity?
Also, as a little bonus question: the first-ever direct image of a black hole, published today, appears to be oval-shaped. Is this because the black hole is rotating or some other effect?