I think if you were 5'10 and 175 and had to fight some 6'5" and 220 your tune would change.
Flip side is that generally speaking I do agree with you that in today's game there is no real deterrence. Rather I see it as settling things down early.
Lets say Brown starts running around in the 1st, Dylan smacks him around. I'd venture a guess he's less likely to continue to do that.
Players are smart. The Lightning were carrying 11 forwards, going down to 10 for 5 minutes early is something teams can recover from. Going down to 10 forwards for a 2nd time puts a good deal of pressure on the remaining ten (even if they can move one of the D to F)
guys that run around like Brown tend to play it a bit more straight when smacked around, moreso when smacked around early.