Look madara and hashirama were already getting on the sage of six path's level with there technique's.It is true that the sage is the first person to change the ninja world and to have inhuman power but he is not the only one.
You have to understand that the sage doesn't have very jutsu and he has only basic jutsu's that are powerful he only modernized the world with the chakra natures and developed the clans.
Once people hear that he changed the ninja world you automatcially assume he is the strogest one to ever live but that is proven wrong once madara took hashirama cells.Madara only took hashirama cells to gain power in truth madara didn't care about what people thought of him in that age only about what would happen to him in the future the strength of the elder son and younger son. Madara has now obtained this power.
By doing this madara is already on the sage's level or atleast near.
then you have to think of all the other created jutsu and other Kekkei Genkai that has been created threw the clans after the sage's death.
clans after the sages death only got modernized and so then created scrolls and kg and so secrets so that there clan can inherit these gifts and it changes over time in some cases gets even more advanceded over time making the jutsu's in the past noting compared to the newer one.
Madara and the sage are both good with the rinnegan they both use or celestial objects from space.Many of you like to say madara does not have alot of chakra it was first mention that madara had some sort of special chakra from birth so mmadara chakra is powerful.
madara and the sage both have good experience from the tailed beast and knowledge of the world.Madara also has the kg that the juubi that the sage doesn't evn have which is the sharingan.
madara can use the ultimate suusanno as an edo but what can sage of six path do use izangi or any other genjutsu to stop it while madara has that abitly as well.
also with susanno it has funijutsus skills as well so the sage's rinnegan can't absorb
madara has every technique that the sage can use and can caopy the sage's tech's with his sharingan too.
Madara can literally have perfect vision if he used wood clones since he has a sharingan and rinnegan by seeing incomming attacks and seeing them from every angle.
madara can do what ever the sage can and can beat or atleast make the sage waste his chakra to death.
here's a summary:
madara can use wood release,rinnegan,Eternal mangekyou sharingan,sharingan,Unlimited chakra and modernize jutsu's, powerfu/special chakra.
while the sage can only use the rinnegan and ten tails chakra and basic jutsu of the nature types.
