The NHL salary cap was introduced to the league after the 2004-05 lockout to ensure that smaller market teams can stay competitive against the big market teams. It has surely helped the league as a whole, but also leads teams to facing issues in keeping their core players.
If you do a good job building your team through the draft, there will inevitably come a time when your young players’ entry-level contracts and bridge deals expire and they seek new deals into the millions. The Colorado Avalanche did a good job locking up key players long-term for fairly good prices.