Common wisdom seems to be that it’s better to carefully muddle mint as opposed to shredding it which releases bitter, vegetal flavors. However I’ve also seen many recipes like this one calling for shaking with mint, or even muddling before shaking, which shreds it up either way. Wouldn’t it be better to stir, roll, or throw instead?
There's generally no need to muddle mint prior to shaking as with good ice and a vigorous shake, as you say, the mint is pulverized anyway. (Guess that's where this cocktail gets its name Smash from.) If you want to more gently infuse mint, then simply add leaves to your spirit for a good hour or so before making your drink and strain before using.