In terms of low- and mid-level fighters, Konoha was definitely outmatched in a four-front war.
But Konoha's elite fighters and Medical Ninjutsu were simply too strong to ignore.
The four great Ninja Villages could attack Konoha's camps, but taking them was another matter.
Beyond veterans like Orochimaru, Tsunade, and Jiraiya, the younger generation had grown strong as well.
Kushina, Mikoto, and Minato Namikaze could each hold their own now.
Minato Namikaze had made his name in the war against the Stone Ninja by using Flying Thunder God to kill fifty ninja ranked Jonin in one stroke, though their actual strength was probably closer to special Jonin. He had earned the title Yellow Flash.
The details differed slightly from the original story, but Minato Namikaze had still become famous.
Konoha had plenty of elite fighters. Even when they could not win, they could cover a retreat, and with the right tactics, they could ambush and eliminate large numbers of the enemy's low- and mid-level fighters.
A counteroffensive was harder. With too few low- and mid-level fighters, even Konoha's elites did not dare take the initiative against the enemy villages.
And so the war became a stalemate.
But Konoha could live with that.
Konoha's emphasis on Medical Ninjutsu had given it a much stronger medical system than the other Ninja Villages.
Someone had once compiled figures from the battlefield.
A Kumogakure ninja wounded in battle generally needed no more than a hundred days to recover before returning to the front. If recovery took longer, the injury was usually permanent, and the ninja could not return.
For Iwagakure, it was three months.
For Sunagakure, it was two months and a week.
For Konoha, it was two months.
As for why Kirigakure was not on the list...
Under Madara's control, Mist Ninja who were