D&D General Feat Observant

[Li Shenron]

Not quite

It never actually say to compare a DC to the passive perception, just "use" the scores. One could easily make that assumption, but the section on passive checks never clarifies how to use the

Ok I don't want to argue that passive check rules are solid because they are NOT, as I said I believe they were thrown into the game without enough consideration... but that section you quoted says "To set an appropriate DC for the check, see chapter 8." and how can you argue that setting a DC doesn't imply to compare it with a check result (whatever the method to calculate it, rolling or passive) is beyond me... I don't remember with certainty but I don't think the books even suggest to roll DC as a variant. "Compare with DC" is pretty much established at the beginning of the ability checks rules section, and passive checks are a subsection of that section.