Just wondering...
Because the manga puts him above several of our current top shinobi/kunoichi

"There is no shinobi alive today who is as powerful as the First Hokage, Senju Hashirama"
DSM Kabuto outright admits that he is inferior to Hashirama. This can also be used to say that EMS Sasuke, BM/KCM Naruto, and Obito are all inferior to Hashirama; however, it's all how you interpret it.

Edo Madara considers the Five Kage's combined efforts as nothing compared to Hashirama.

Edo Madara calls BM Naruto, Killer Bee, Gai, and Kakashi a half-assed band of ninja, yet he calls Hashirama the ultimate shinobi. That puts him above them, does it not?

After reading this, just how powerful was he?