First of all, there’s no “assumption” being made, and in this particular case I made it extremely clear that my question wasn’t “coming from” anywhere—it’s just a question. I don’t have an agenda. I was just curious whether someone with some grounded knowledge might be able to shed a little light.

Though obviously horrific, from what I understand, Ebola is rare and occurs in relatively isolated outbreaks. Because it’s so deadly, people respond quickly, and it’s quickly contained, preventing it from spreading very far. Sure, that’s not necessarily the “natural” course, but it’s the reality, and it does impact the virus’ capacity to multiply and/or proliferate. So whether the factors are purely biological or include a social/medical dimension doesn’t matter that much—it’s arguably a “less successful” virus, whose “failure” lies in its tendency to kill the host.