Most tool criticism is polite. A reviewer notes that the pliers are small or the steel is soft and moves on. The r/multitools thread nominating the worst keychain multitool ever made skipped that stage entirely, and the post's author confessed his bias upfront before making the case that nothing beats the hammer multitool for uselessness.
The object in question is a keychain-size tool with pliers on one side and a claw hammer head on the other. The complaint is not that either function is missing but that both are defeated by scale. A hammer needs mass to drive a nail, and a keychain tool weighs less than the nail. Pliers need jaws wide enough to grip a fastener and handles long enough to generate leverage, and the format provides neither. The result is an object that works in the photograph and not in the hand.
There is a real lesson buried in the complaint. Keychain tools trade capability for carry, and the honest ones admit it: a Victorinox Classic or a Leatherman Micra offers a blade, scissors and a screwdriver at a weight nobody notices, and none of them pretends to replace a real tool. The gadgets that fail are the ones that promise a full workshop in 40 grams, because the promise forces the designer to include functions that cannot work at that scale.
The comparison worth making is between a keychain tool and no keychain tool. If the alternative is nothing, a mediocre screwdriver beats a fingernail. If the alternative is a $30 compact multitool in a pocket, the keychain gadget is dead weight, and the hammer version is dead weight shaped like a joke. The thread's real value is as a reminder to judge multitools by the fraction of their functions you have actually used, not by the number printed on the package.