There is sometimes a mercenary approach when it comes to the WJC but I don't think that it's generally viewed as a business decision. For most of these players, on the big teams, it will have no bearing on their professional careers. What Eberle says here:
Can You Believe It?!' Jordan Eberle and Canada’s World Junior Miracle - TSN.ca
"You really have two dreams growing up playing hockey in Canada: to play in the NHL and win a Stanley Cup, obviously, and to play for Canada at the World Juniors"
May not be true for all Canadian players but it is true for some. It's clear that Dach was in Edmonton due to his desire to play in the 2021 WJC regardless of his NHL career. It's unfortunate that he sat in quarantine for weeks when he could have been doing other things and then broke his wrist before the tournament even started. Obviously Chicago regrets releasing him now given almost the worst case scenario happened but teams will continue releasing players for this tournament in the years to come.