Although Lazeez words it nicely...
He didn't word it nicely, he worded it precisely. Your quotations are from a section with the caption 'Good Submission Practices', not 'the ironclad rules of coding'.
I'd still agree with you if the only purpose of the coding would be to warn readers but the codes also serve as search criteria, i.e. advertisement of story content. A reader who chose your story because you applied the tag 'Voyeurism' is just as likely to punish you with a bad score if the only voyeuristic scene happens on page 447 of your epic-length novel. In my opinion, the low score would be justified for false advertisement.
Personally, I only tag as a warning of story content, while I omit tags which are applicable by definition but I deem neither squick-worthy nor relevant to the story.
For instance, these are the codes and tags I applied to 'Law of the Blood' (Story Size: 936kb):
Sex Contents: Much Sex
Ma/Fa, mt/ft, mt/Fa, Fa/Fa, ft/ft, Fa/ft, Mult, Magic, Mind Control, NonConsensual, High Fantasy, Incest, Brother, Sister, DomSub, Rough, Harem, Anal Sex, First, Size, Slow, Violent
These are the tags applicable by definition but I omitted:
Consensual, Reluctant, Romantic, Slavery, Lesbian, BiSexual, Heterosexual, Vampires, MaleDom, FemaleDom, Light Bond, Spanking, Group Sex, Polygamy/Polyamory, Interracial, Black Female, White Male, White Female, Analingus, Cream Pie, Exhibitionism, Masturbation, Oral Sex, Petting, Squirting, Tit-Fucking, Voyeurism, Big Breasts, Public Sex, Small Breasts, Prostitution, Royalty, Transformation
... yes, all descriptive and on-scene.
The story was completed in 2012 and about 20,000 people read the complete story since then. It has a score of 8.30 and no one ever complained to me about a missing code or a code I wrongly applied.