Li Hong's current mana surpasses that of an average Heavenly Immortal, but his realm is far from the Yang God Perfection of a Heavenly Immortal. He can still attain rebirth in the Nirvana, but can only fluctuate within the three grades of the Middle Class in the Three Classes and Nine Grades.
The barrier between the two worlds is so strong; when Deng Yin once traveled from this world to Earth, he first had to develop followers there, accumulate willpower, and finally rely on the amassed willpower of his followers to descend to the other world. Upon returning, he needed Shi Feiyang's help.
Gongye Huang made a vow to ascend to Earth in the form of ascension.
Lu Yu could spy on Earth but couldn't cross over.
Though Xin Ru manifested avatars in many Buddha Country Pure Lands, the true body still couldn't cross over.
Only Golden Immortals can cross the world's barrier relatively easily, but this ease is only relative.
