Iirc Naruto mentions hard work and no shortcuts to Obito when trying to talk no Jutsu him.
That statement didn't have anything to do with power. Especially when the previous Hokages had some sort of "heritage/shortcuts" you speak of. Naruto was referring to the fact the Obito was trying to escape from reality and his true self. Thus, Infinite Tsukuyomi being a shortcut. Lets look at some examples:
- Hashirama was Ashura's previous transmigrant and was a descendant of the Senjus. He was also born with one of the most versatile and powerful Kekkei Genkai (Wood Style). He had quite a prowess of chakra as well, thus having Sage Mode. This can be considered a shortcut, given that he was actually powerful naturally.
- Tobirama was born into the Senjus, but wasn't Ashura's incarnation. But he was a genius to the point he had invented techniques such as FTG, Shadow Clones, and Edo Tensei. He was the First Hokage's brother, who appointed him; so that's considered a shortcut.
- Minato basically gained the technique from Tobirama as well as gaining teachings from Kushina. He was considered a genius of the decade by several characters.
These are examples of why relating the shortcut statements to power is flawed.