Because of the high attrition rate? It seems to lack protection but that's why it was more maneuverable. Apparently, it was designed for sharp turns, flying low and breaking for tree cover. I wouldn't want to be in one of those.
They could. But it probably has too large an airframe for making quick turns or evading detection as the Cobra did. It seems to be suited for high speed missions across large areas.
We will be covering much more, not limited to American wars. Next, we'll cover the Mirage fighter jets. Later, Harriers, Sea Kings, Chinooks, F86 Sabres, Starfighters, MIGs, and so on.