its because a summoning is different from edo tensei,
edo tensei requires ANOTHER CHARACTER to fight, and giving another characters feats to kabuto/orochimaru is definitely invalid,
a summoning and bijuu are different since they fight alongside the character and most of the times have a contract, not to mention that summonings themselves are never considered in top ten lists, (which is where my quote is taken from), and entities such as the juubi itself arent in the top 10 either despite it being very capable of doing so,
people discard summonings in their top 10 lists everytime, yet when Edo Tensei is discraded despite the fact that ANOTHER character is fighting and despite the fact that the feats displayed from that character shouldnt be going to the ET user,
people seem to be going crazy, when its even worse to include them
and including edo tensei in top 10 is even worse based on the fact that there are too many varibales to consider,
madara using the kyuubi was counted due to the fact that he had a summoning with kurama, and could control it as well as use his OWN arseanl with it, such as covering it with PS
furthermore his victory wouldve counted because him using kurama is still the same as naruto using his,
I'm sorry, but your logic is entirely flawed.
For one thing, it can't be said that Kabuto knows Jinton by extension of controlling Muu, it's still Muu's ability, but Muu is only fighting because of Kabuto's power. His spirit is bound to the land of the living by Edo Tensei, so he literally exists because of Kabuto's power, and his actions are dictated by Kabuto's power. He is no longer a person, he is an animated corpse with no free-will, he is a tool. While he has a consciousness (if Kabuto allows it), he has no control over himself. He is aesthetically no different from a Pein body, or Sasori's puppets.
Kurama does not have a contract, he's simply being controlled by Uchiha/Senju powers. Summons do have contracts, but they are not controlled and can still choose to obey or not. They are both outside presences, but are brought into battle by the power of the user, the power of Madara's eyes or the power of the user's contract. Edo Tensei is just like them, with the exception that the Edo Tenseis are NOT outside presences and only exist because of the power of the user. Hell, Black Zetsu is an outside presence helping Kaguya, but he exists because of Kaguya's power.
In all three cases, Bijuus, summons, or zombies, they are tools of the user because it requires their power to use them.
Kurama is binded to Naruto's soul, Madara just walked up to Kurama and said "You're coming with me."
Besides, it's peoples' choices not to include Bijuus on top ten lists, opting to only use people, but that is no excuse. Edo Tensei is very straight-forward, the only real variable is who's resurrected.