yes, they will follow a warmongery leader easily as it's in their culture.
but they also obviously can keep themselves in check even when their kids go hungry under a non-warmonger leader. (which ironically is only possible because of that same warrior culture.)
the hordes need for conflict is a river. a good leader can channel the course of the river into productive areas, a bad leader can break all the dams and cause a massive flood.
if the elves and humans had been smarter about it, they could have had a lot more influence on who succeeded thrall, and thus what conflicts could have been avoided.