The more important reason was that at the instant of enlightenment, one was the most connected to the Heavens they could be. The concocting of Immortal Grade Pills was a process of snatching Heavenly Daos from the Heavens themselves, this was how Endowments came to be.
Refining Ri in this way while she was in a state of enlightenment allowed her body to swallow up heavenly daos even better than a high grade cauldron could. If the immortals of the immortal plane knew such a thing was possible, they would fall over one another in an attempt to be next in line.
Dyon simply didn't realize the gravity of the path he just forged. What he didn't know was that even his former pinnacle self had not managed to create such a thing. Without even knowing… He had surpassed a version of himself he didn't even know existed yet…
These two factors together was what helped facilitate the last… The World Tree lowering its guard…