Lenght of stories?

Hi all

Normal book lenght is somewhere between 70k-120k I saw that many author post 200k+; 500k+ words per story. How and why? Even the Lord of the Rings trilogy have less than 600k+ words.

Is Roayal Road audience addicted more to the raw lenght then the quality of the prose and the story? 500k can not be editet in high level. Or this is not important here for the readers just have story about their pereferred characters?