Well, it is a decent article. However- and yeah, of course it's a matter of taste- but honestly, only a few of those monsters qualify as amongst the dumbest D&D monsters, IMHO.
The roving mauler and duckbunny? Sure. Maybe the flumph. But the flail snail? The paeliryon? The thought eater??? Yes, they have their limitations, but they're awesome!
IMHO such a list ought to include certain creatures, no questions asked:
- Pseudo-Undead (1e MM2)
- Throat Leech (1e FF)
- Pernicorn (1e FF)
- Astereater (2e Spelljammer)
- Spanner (2e FF MC appendix)
- Tooth Beast (3e Tome of Magic)
Sure, it's a matter of taste, but I think that the flumph, achaierai and stench kow all have great uses- not every monster should be super-deadly (hi, flumph!) or for common consumption (if you're in Hell, it's nice to see the food chain). The ones I list are useless creatures that are unlikely to see official appearances again in the future, and for good reason! With the possible exception of the astereater, which can arguably fall into the same category as the stench kow, these guys are completely useless, at least as monsters- the throat leech and pernicorn can, arguably, make good environmental hazards, but how do you stab a monster that's stuck in the back of your throat?