In the old days, many competitions required the photographer to submit the images on slides. The contest organizers didn't want to be responsible for a large number of prints and the slides were easier to handle and view. The slides were never as good as the final print.
I would much rather submit a digital file over a slide.
+1. This is why a bit of skill on digital tools is useful, to approximate as much as possible what your silver print looks like.
To me the ease of entry, for contests literally the world over, is a gigantic advantage and a huge gain for photographers.
"Never criticize someone until you've walked a mile in their shoes. That way, you're a mile away and you've got their shoes."