Let's say you have a wood-framed wall with cement-based stucco cladding and it's in pretty good condition, with a few typical stucco cracks. If you wanted to seal the cracks, add another layer, and change the color, could you apply surface-bonding cement instead of a (much more expensive) additional layer of stucco?
Yes as an exterior (no as an interior).
The general rule is that the hardest surface must face the side that water would be attacking from. If you reverse it, any water that penetrates cause a pressure build up when it meets the harder surface and cause the softer material to crack.