The poster is doubtful "an idiot" for posting something that is a serious attempt at solving spam. Sure the idea won't work, but if coming up with a successful solution to fighting absolutely every spam message was so simple we would already have been solved, no?

Secondly, the form letter offers a terse list of not only the pitfalls of this particular approach, but a checklist of other things to consider when responding with "well ok what if I change $something?".

Thirdly, it's a subtle nudge saying "lots of people have already thought about this stuff, why not have a looksee at other work in the area and learn from people that have gone before you", without calling them out and getting all nasty.

Finally, levity isn't a misfeature.

Good day, ( ) sir / ( ) ma'am.