Hiruzen knowing every single technique in Konoha is a bunch of bull.
Do you really think Hiruzen can use the Nara's, Akimichi's, Yamanaka's, and the Aburame's clans' secret jutsu? Or the Uchiha and Hyuuga's Doujutsu? What about Yamato's Mukuton? If we exclude these secret techniques and KG, that's already at least half of the jutsu in Konoha in his time.
So can Hiruzen use all the jutsu in Konoha? If so, he must have all 5 basic chakra natures: wind, fire, water, earth, and lightning. Something only Kakuzu has shown so far, but by taking other peoples' hearts, it's that advanced. We've seen him use only fire and earth.
If he was also able to use wind, can he perform all of Danzo's very powerful wind techs? Or Asuma's powerful wind tech?
Can he open up the 8th gates or summon Guy's turtle?
Can he use Lightning Blade or Rasengan?
Can he use Water Dragon and Giant Vortex Jutsu possessed by Kakashi?
Can he summon the toads?
Can he use the great Tsunade's medical ninjutsu or Jiraiya's Sage Mode?
What about Ibiki's torturing chamber or Anko's snakes?
I just doubt he can perform techniques like those, He can maybe do 1/3 of the techs in Konoha, if that. Perhaps when the manga said, "he knew all the jutsu in Konoha", maybe they were referring to him being very knowledgeable with them by knowing their strengths and weaknesses, and other characteristics.
Do you really think Hiruzen can use the Nara's, Akimichi's, Yamanaka's, and the Aburame's clans' secret jutsu? Or the Uchiha and Hyuuga's Doujutsu? What about Yamato's Mukuton? If we exclude these secret techniques and KG, that's already at least half of the jutsu in Konoha in his time.
So can Hiruzen use all the jutsu in Konoha? If so, he must have all 5 basic chakra natures: wind, fire, water, earth, and lightning. Something only Kakuzu has shown so far, but by taking other peoples' hearts, it's that advanced. We've seen him use only fire and earth.
If he was also able to use wind, can he perform all of Danzo's very powerful wind techs? Or Asuma's powerful wind tech?
Can he open up the 8th gates or summon Guy's turtle?
Can he use Lightning Blade or Rasengan?
Can he use Water Dragon and Giant Vortex Jutsu possessed by Kakashi?
Can he summon the toads?
Can he use the great Tsunade's medical ninjutsu or Jiraiya's Sage Mode?
What about Ibiki's torturing chamber or Anko's snakes?
I just doubt he can perform techniques like those, He can maybe do 1/3 of the techs in Konoha, if that. Perhaps when the manga said, "he knew all the jutsu in Konoha", maybe they were referring to him being very knowledgeable with them by knowing their strengths and weaknesses, and other characteristics.