Splinters are a painful bollocks to remove cleanly with a bushcraft knife, you’re more likely to remove the poor wee finger than the splinter. Burns are horrible if left to blister and burst un protected in the woods. The tiniest bug bite becomes a torment if scratched with a dirty fingernail triggering a histamine response. Cuts can range from annoying to fatal very, very easliy when you are far from a helpful passerby.
These are the reasons I carry a first aid kit anytime I’m out.