The thought process of the members of the Five Sects was extremely simple. The Heavenly Phoenix Divine Maiden was only at the consummate level of the Sun Moon Tier, so they would definitely be able to contain her—if not suppress her—if enough of them charged over.
However, their understanding of the Heavenly Phoenix Divine Maiden was restricted to what they knew about her several thousand years ago.
At that time, the Heavenly Phoenix Divine Maiden had chosen to go into seclusion after deciding that she had already repaid the Cloud Phoenix Sect. Back then, she had only been at the high extreme of the Sun Moon Tier.
Many years had now passed, and the Five Sects all knew that she had already advanced to the consummate level. However, they speculated that she was at most at the early stage or middle stage. After all, the higher one's cultivation, the harder it would be to advance.