I try to never be without a little ziploc bag of toilet paper. You don't need much, just a couple feet, it's easy to replenish the supply at gas stations or restaurants.
Beyond the whole airborne-outbreak-fly scenario, it's just common sense to dig a foxhole to defecate in, any animal does the same. Shit is not esthetically pleasing, it smells bad, attracts pests, someone (you) might walk in it.
Not digging a hole or at least covering well is really only acceptable from someone who doesn't know better, not something to aspire to.