Saw a sin bin once the whole season. Still saw the same amount of dissent. Still saw refs who (I don't want to say scared so...) didn't give sin bins consistently throughout a game because it would've been controversial or had a massive effect on the game etc.
The problem isn't a lack of existing punishment for dissent, it's that refs do not apply it. And refs do not apply it consistently week by week, which means they all slowly get more lenient. The same thing has happened in the Premier League since they implemented there no approaching the referee rule a few seasons back. Can't remember a card for that since Rooney got one on day 1.