Unfulfilled potential ... or how not to adapt a book

so the novel wasn't exactly a literary masterpiece, contained little plot and long exposition, yet it was entertaining and had a satirical vibe going on. the movie even emphasizes the weaknesses of the book, while not making much out of the "dramatic" aspects of its source material.

the affair between mae's character and the enigmatic stranger, leading to the major twist reveal towards the end of the book? in the movie that storyline had no suspense at all and the reveal was presented already after the third act of the movie.

mae's obsession/strain to climb in the participation rank and generally to become more popular? the participation rank was established in the movie - but the effect of it on mae was hardly shown subsequently.

mae accidentally exposing her parents when [spoiler] they're engaged in sexual acticity inside their home and mae steps into their room wearing a webcam [/spoiler] ? in the movie it's just part of a montage and mae [spoiler] doesn't even physically visit her parents in that scene - she just checks out a webcam which is already installed in her parents' room from a monitor - so the parent's don't even notice it while their privacy gets intruded. [/spoiler]