It will accomplish informing people that they are indeed being exposed to sound loud enough to cause permanent hearing damage. I think a surprising amount of people don't quite grasp that reality.

Also you can get the best noise reduction rating (33dB) earplugs for well under a dollar, I last ordered 25 pairs of disposable foam plugs for ~$0.50 a pair at $13 total. So while it's totally expected for some venues to be scummy and still offer shitty plugs, I'm hopeful that the majority of them will take the over 100% profit on the $1 price or under.