Some related phrases: * "We already tried that." * Once bitten, twice shy. * Not giving the idea a chance; not giving it a fair shake. * Giving up on an ide

Some related phrases: * "We already tried that." * Once bitten, twice shy. * Not giving the idea a chance; not giving it a fair shake. * Giving up on an idea too easily. * Closing your mind to a possibility. For what it's worth, I think both the poor implementation and the wrong conclusion can be either deliberate or accidental. In this case, the poor implementation was almost definitely accidental, and most likely the reporter isn't actively trying to discredit the idea; they are just leaping to a conclusion. So the best phrase might be vary depending on whether it's just poor reasoning or an underhanded attempt to manipulate people's views. Also, on a tangent, there's probably some validity to this kind of reasoning. Sometimes in problem-solving there are almost an infinite number of things you could try. If you spend all your resources going down one particular rat hole that doesn't seem to be working, you may never move on to exploring the rest of the solution space. In practice, it can make a lot of sense to essentially do a breadth-first search of possible approaches. The error isn't in using a breadth-first order; it's in deleting things from the FIFO queue of stuff to try eventually (or never adding). And the other common error is in assuming you can't or shouldn't try to do both in parallel.