I was under the impression that it's not so much about America being responsible for every bad thing in the world, but that historically America has been taking advantage of those thousands of years of history, culture and of course conflict, to their own benefit.
So if due to some political agenda there is profit or benefits to be reaped from nudging certain conflicts this or that way, there's a high probability that people in power would try to obtain said benefit. I think it's in that sense that "America puts its nose into every conflict around the world".
Not saying that I agree or disagree with that view, but I do think it's a bit naive to say that America is the root of all evil, as much as it's naive to think that the most powerful nation in the world (for different definitions of most powerful) would have no interest in other countries' conflicts or in influencing them to their benefit.
In other words, if for whatever reason an escalation in the conflicts in Syria or other parts of the Middle East (or the world for that matter) could benefit the US, would it be so far-fetched to think that they would have a vested interest in creating the conditions for that escalation to actually happen?