Edo Tensei can't be related to summoning jutsu....
Summoning jutsu: requires a blood contract with a specific creature, after that user can anytime summon or un-summon his summon AND if the summon is defeated somewhere, it is automatically reverse summoned for the restoration...
Edo Tensei: requires DNA sample of the body whose unsatisfied existing soul is to be summoned from the impure world, once contract is made user can summon that soul within any available body and un-summon it until or unless that revived soul or simply Edo finds the satisfactions from the pure world or is sealed away.... After that, Edo is un-usable for the future thus excluded from the list of the Edo's once a person had...
A/c to this, major of the Kabuto's valuable Edo's are sealed away or turned good...which means Kabuto has only Ramen guy left for the ET...SO, still considering ET Kabuto's major asset is BS..
Kabuto is now same as w/o ET and w/o ET, Kabuto sucks...