[chongli]

I am seeing this claim a lot, but I do not understand it. Why would readers assume that a riddle is a bunch of nonsense, rather than something with an objective answer?

Different people carry different assumptions with them throughout their lives. Not everybody approaches a logic puzzle with the mental preparation of solving logic puzzles. They aren't looking to analyze the statements and they don't carry the assumption that the statements carry just enough information to solve it. Instead, they might expect some trick or play on words to give a "stupid" answer.

because I had no trouble understanding the wording of the puzzle

But you do have trouble understanding that other people might be different from you; with different experiences, assumptions, etc.

[andrewprock]

"But you do have trouble understanding that other people might be different from you; with different experiences, assumptions, etc."

In essence, this is the true test of the puzzle; not whether you can solve the intended puzzle, but whether or not you can muster sufficient social and analytical empathy to work with others when your assumptions turn out to be incongruent with the intended assumptions.