Not quite the case. While your life didn’t mean much, generally speaking, the limitations on military action in the pre-modern period come down to logistics - ie how many troops can be fed in a field army at once.

When there’s a limit to what you can do with numbers, you have to put some effort into quality. So SOME amount of equipment was considered necessary - the idea of the mass peasant levy carrying pitchforks and clubs only really comes into play for the most small-scale of intrafeudal and clan wars and the like, and even then, not always - unmotivated troops are quick to collapse against well-armed enemies. There are incidents of some particularly poorly-thought-out peasant rebellions being eliminated by mounted knights that they outnumber 20-1, or more, simply because, in a pitched battle, equipment and training DOES make a massive difference.

Even the uglier and more primitive forms of pre-modern states would generally see troops sent into battle with, at minimum, a metal-tipped spear and a shield. Even as far back as Ancient Egypt.