I have always played with a shoulder rest, so it’s so awkward for me to play without it. But i guess it is just a personal preference, i don’t feel there are any setbacks either way as long as you learn to adjust to either using or not using one. However, I have heard that shoulder rests affect the natural sound omitted from a violin (something to look more into, i may just be speculating). I feel some people think they look cool not using one, however i don’t really agree with that. I know that back in early times of the violin’s usage, shoulder rests hadn’t been invented.