But that won't work for shops trying to avoid taxes. It'll also make it much harder to buy stuff from criminals, as you would have to go get cash somewhere.
What other cash exchanges still happens?
Sure, their big ticket items are still going to be hotels and the like, where they will pay with a credit card, but they are not interested in coming if they can pay the small merchant with cash. Because they don't have access to the local infrastructure for digital payments, that the locals do.
I never travel abroad without cash, and that includes when I travel to Sweden.
I've been in Sweden plenty times and haven't even seen a single Swedish krona. In the Copenhagen subreddit we also recommend people not bringing in cash, at least as long as their credit card situation is somewhat reasonable.