"The earlier one achieves Taoist Monarch status, the sooner they can gain more initiative."
This is the consensus among the powerhouses of the True Martial Sect. In order for the True Martial Emperor to achieve Taoist Monarch status sooner, they have mobilized almost entirely, going all out like the previous plan to replace gods with humans.
Unfortunately, they couldn't provide the equivalent costs that the Xiao Sect needed and couldn't acquire those items to help the True Martial Emperor achieve Taoist Monarch status.
At this time, the Jade Emperor approached voluntarily, telling them he could provide what was needed to help the True Martial Emperor achieve Taoist Monarch status.
And neither the True Martial Emperor nor the True Martial Sect needed to truly form an alliance with him, nor join the Jade Emperor's campaign.
At that time, the True Martial Emperor and the True Martial Sect truly had no reason to refuse, even if they knew it would cost them something.