That terse summary is basically misleading, so I can see why it's not helpful. It would be a much better one line summary to say "Complex numbers were invented

That terse summary is basically misleading, so I can see why it's not helpful. It would be a much better one line summary to say "Complex numbers were invented so that we could name (and describe) all roots to a quadratic equation" of course that also requires further explanation, but at least it's not leading the reader down the wrong path.