I'd imagine grown nails wouldn't fare well while working farm tools or holding a sword. Did they have ancient nail clippers? And when were the first nail clippers invented?
I see by your question that you have never worked with your hands. When you engage in manual labor the constant friction keeps your fingernails worn down. I presume that going barefoot would do the same for your toesies.
hi! FYI you'll find some examples in the FAQ (link on sidebar)