“Dumbledore can’t beat Voldemort” to me means that he can’t beat the horcrux network, not that he can’t win against Voldemort in a duel. But that would be winning a duel, not winning the war.
“Dumbledore can’t beat Voldemort” to me means that he can’t beat the horcrux network, not that he can’t win against Voldemort in a duel. But that would be winning a duel, not winning the war.