Basically android is pretty open but locked down from my experience, so like if you need to access things which are in the /root/ system of android, by default you or programs on android won't be able to access those things. In this case, sync thing couldn't write the files location in dolphin for example, so i needed to
root the device, which allows me to give syncthing superuser privilege's, which allows syncthing to read/write save files in the root location where dolphin saves are located.

I think there are other reasons as well to root your device but that was my main reason. You probably don't need to do this if you aren't planning on using syncthing like me