According to the six-level role set by Huo Ying in his later period, it is easy to suppress reincarnated individuals. In order to ensure his own individual advantage, Uchibo Shoko Asahara had to seek to get rid of reincarnated individuals.
Any ninja skill in Naruto has advantages and disadvantages, and pollution metempsychosis is no exception. Although the polluted metempsychosis has strong resilience to physical attacks and infinite chakra to conventional ninjas, the six-level role of Naruto in the later period can still cause irreversible damage to the polluted metempsychosis.
The most obvious example is that Namikaze Minato, who is in a filthy state of metempsychosis, is completely suppressed by Liu Daodai, which can directly and irretrievably harm Namikaze Minato's soul. Therefore, in fact, if Uchihiro Shoko Asahara continues to be filthy and reincarnated, there is no way to cope with the two Mingzuo who have the aura of the protagonist and finally get the talent of Ootutuki Hagoromo. Therefore, in order to avoid being suppressed, Uchibo Shoko Asahara will choose to be reborn from the filthy soil.
On the other hand, even though Shoko Asahara, as a reincarnated individual, has a high degree of autonomy in his actions, he is still controlled by the reincarnated summoner in the final analysis. In order to realize the ultimate infinite Harle plan, Shoko Asahara, Uchibo, will definitely exclude all factors that may affect his realization of the above plan.
In this way, it is a necessary step to realize the real resurrection naturally through reincarnation. Uchihiro Shoko Asahara had fused the cells between columns before his death, and he had the threshold to enter a six-level figure. In order to develop the strength and new ability of Band 6, Uchibo Shoko Asahara's filth removal is a necessary process.
Uchihiro Shoko Asahara wants to be the pillar of ten tail, and Harle needs conventional flesh and blood.
Uchihiro Madara's plans are actually aimed at realizing infinite Harle. In the plot, the opening of the infinite Harle at night is completed under normal circumstances, while the resurrection of Uchibo Shoko Asahara in metempsychosis can only be regarded as boarding his soul in the carrier of the living. Whether he can successfully become a pillar force in ten tail and open up infinite Harle is still unknown. Looking at the six-level suppression metempsychosis paved in the early stage of the plot, it is not high.
Therefore, it is speculated that one of the purposes of Uchihiro Shoko Asahara's metempsychosis is to successfully open the infinite Harle and become the pillar force of ten tail. Of course, it does not rule out that Heijue can successfully suppress Uchibo Shoko Asahara in the final stage in order to better control what Uchibo Shoko Asahara deliberately left on the stone tablet.
The conditions for launching the Infinite Harle in Huo Ying are very harsh. In order to ensure that Uchihiro Shoko Asahara can successfully become the pillar of ten tail and open the infinite Harle, he must get rid of the filthy metempsychosis.
Finally, to sum up, I personally think that the reason why Uchibo Shoko Asahara got rid of metempsychosis is to overcome the innate disadvantage of metempsychosis for the role of level 6, and at the same time get rid of the control of the summoner of metempsychosis. On the other hand, it is to prepare for the successful opening of Infinite Harle. Please forgive me if the analysis is not in place. If you have other ideas, please leave a message to discuss.