I can't see that poster's posts, but I am very familiar with that section of the DMG.
Secret doors and traps are in my view different, though one could argue they both work as per the rules for finding hidden objects (Basic Rules, page 64): "When your character searches for a hidden object such as a secret door or trap, the DM typically asks you to make a Wisdom (Perception) check." This section also sets forth a requirement of reasonably specificity for finding hidden objects.
The section on traps in the DMG is in my view poorly written and edited as it sits in contradiction to the rules for passive checks. The specific line you quote really works only in the context of Activities While Traveling (Basic Ruls, p. 67-68), which is how I presented how I handle such a thing to @Elfcrusher. This section conflates actions and checks as D&D 4e does. It refers to "active" and "passive" tasks which aren't a thing in D&D 5e but are a thing in D&D 4e. In order for it to work, one has to be running a game like D&D 4e where a passive check represents a character not making "active" use of a skill. Which is fine, if that's what one wants to do. I do not (being a proponent of running each game distinctly, according to their rules) and I don't think it's possible to square up the DMG with what the rules for ability checks and passive checks say outside of something like Activities While Traveling.
I freely acknowledge that the rules may not be as tightly written as one would like. But, poorly written or not, I think the inclusion of these rules is strong evidence against your claim that passive tasks aren't a thing in 5e. If they're in the books, doesn't that make them part of this edition?
By my count, there are at least four explictly-supported uses for passive perception in the rules:
- To resolve repeated tasks.
- To avoid rolling dice during task resolution.
- To notice hidden traps, doors, etc.
- To set the DC when opponents try to remain unnoticed.
That’s a very good point.
I don’t do it that way. But the rules say you can. I’d argue it’s better not to because I like it better when players make decisions and take actions than when the system simply drops something into their lap (as can happen when an adventurer’s passive perception “pings” a trap).
Likewise, I feel the overall difficulty in 5E is rather low. And there are a number of little nerf-foam pads in the system I’m not fond of. But that’s down to personal taste. And the text here says “you can” and not “you must.” So I think we can all agree on allowances for personal taste, setting, genre, etc.
Absolutely. I don't think it's mandatory at all, I just think it's worth acknowledeging that it's supported in 5e.