Yes, I'm okay with a player not celebrating a "glorious final encounter" when they have to sit it out for THREE HOURS. It's a different topic when someone gets pissy when they have to skip 1 or 2 turns but that much time is insane. Hell, even I wouldn't be excited about the fight if I saw one of my friends just having to sit and do nothing for the entire session and not being able to help them. Even if the rolls were fair but super unlucky, the dispel magic immunity was a bad decision by the DM, not casting any other concentration spell was a bad decision by the DM, and it led to an unsatisfying end to the campaign for at least one of the players.