But did you know this is not the first salary cap in the NHL's history?
In the 1932-33 season the league introduced a salary cap to ensure franchise stability. Each team was capped with a $70,000 payroll. Furthermore, individual salaries were limited at $7,500 per player. To further reduce costs, team rosters were reduced to just 13 players. The NHL even halved it's officiating payroll, eliminating one of the two on-ice referees altogether.
Of course this all came about during the Great Depression. Top players like Eddie Shore and Howie Morenz did not appreciate the changes, as they took big pay cuts. Other players lost jobs completely. And there was no Player's Association to protect them back then.
But the NHL was able to get away with the unilateral maneuvering as there was no rival major league anymore. Furthermore, the NHL secured new working arrangements with minor leagues such as the American Hockey League to ensure that they would not try to poach NHL talent.