But that was what everyone thought before black zetsu confessed that zetsu weren't made by combining hasirama cells and the gedo mazou. But where instead kaguya soldiers brought out from the gedo.
It's likely that more zetsu clones were created from hasirama cells and the gedo but one very important thing to note is that spiral zetsu,the one fused with obito is one of the original zetsu brought from the gedoand not the cloned one. The truth is obito had no hashi cells and apparently for some reason some here seems to be salty about that.
The common misconceptions were:
a) Black Zetsu was a manifestation of Madara's will.
b) General Uchiha + Senju DNA would awaken the Rinnegan.
It's true that Kaguya used the Shinju to form WZ soldiers, but Madara also achieved with Hashirama's DNA. As evidenced by Oro's Zetsu body:
You must be registered for see images
Madara used those cells on Obito to save him, hence why he can use Mokuton, has a huge stamina and why his MS eye didn't go blind (or at least no way near as much) as Kakashi's, despite highly intensive usage. It's also the reason that he has Saisei Noryoku.
What's this in reference to
The time since this subject has ever been questioned...