There is still a lot of need for cash on hand when doing ordinary things in Thailand as a tourist.
That it’s much harder to convert SEK/NOK/DKK notes in Thailand means that there is a need to: convert in Scandinavia; or to have in hand USD, EUR or GBP notes to then convert in Thailand; or to be dependent on using ATM machines in Thailand and accept the involved limits and even risks applicable to bank card use at the ATMs.
ATM use has not only any bank fees involved on two or more sides of the transaction. It also probably has daily cash withdrawal limits. Also, I don’t suggest keeping a huge available balance of funds in your current account tied to the ATM card being used abroad.
I run into a lot of Scandinavian tourists in Thailand -- and sometimes in some of the Thai resort places during peak peak periods it’s been more Scandinavians than Americans. And yet for various reasons those places too have gotten out of the SEK/NOK/DKK cash conversion business but still take USD, EUR and GBP.