This is a "hot take"... but honestly, reasonably well rooted.
Nashville was not a paticularily good team last year, and still have $11m in dead cap this year between Johansen, Ekholm, Duchene and Turris. That's a lot of dead cap to overcome in a playoff round. Even next year, Johansen is off, but there's still close to $9m in dead cap. It doesn't become managable until year 3 with Duchene's penalty decreasing, where they've got $3.5m in dead cap.
Now you go ahead and look at their "core" who is locked up for the next 3 years.... and their ages.
Forsberg, 29 years old, $8.5m
Stamkos, 34 years old, $8m
Marchessault, 33 years old, $5.5m
O'Reilly, 33 years old, $4.5m
Novak, 27 years old, $3.5m
Josi, 34 years old, $9.06m
Skjei, 30 years old, $7m
Carrier, 27 years old, $3.75m
Saros, 29 years old, $7.74m
There's a lot more guys (and a lot more money) that are on the tail ends of their careers than those about to enter their primes.