Measuring your game by playtime is, itself, the problem. If your game has an expected playtime, you failed.
Games are challenges. Playtime varies wildly. Many oldschool games are *technically* less than an hour long, but will take people weeks or months to beat, as they require learning, both recognizing patterns mentally and building up muscle memory. Then there's games like Civilization or any multiplayer game were there's basically no end.
Trying to define a playtime derives from the idea of games as cinema, and is one of the worst parts of how the game industry started evolving in the 2000s.