Being a "yes, if" person, I can tell you that most of the times I reply with that, everything else is taken as a joke. the more complicated the problem, the more of a joke it seems to the others.

After all, they want a simple "yes, we can". If they hear about the half a dozen other problems that need to be solved first, they think "oh, yeah, that would be great, haha. But we won't do it because we want to focus on solving E, not A, B, C and D"...