The difference between a hard cap with a floor like the NHL has and what the MLB has is the Oilers are much more likely to be able to retain Connor McDavid for the entirety of his best years and build around him, where MLB and NBA teams often act as feeders. In the NBA, the one thing you can say is that it's not necessarily built around big markets. Oakland is one of the worst cities in North America, but Golden State is the god-tier franchise. In the MLB, big deals are handed out based on need all the time, but it's not unheard of for the biggest deals to come down in Boston or New York.
If salary disparity were less of an issue, then having so few playoff teams would likewise be less of a problem. If the MLB were the NBA or NHL, it would struggle because it's inherent advantages in surviving in that system are unique to baseball. Tickets can't be that cheap for an arena sport and games can't be that chill.
Keep in mind that as the NHL expands to 32 teams, many people inside the sport and out believe the NHL playoffs should extend from 16 teams to 20 teams.