The answer to ill-informed speech is more speech

It's not and due to a simple reason: people with ill intent do not play by the same rules. People throwing conspiracy theories, lies, distorted truths and all sorts of disinformation don't care about being right, they care about reach and strong emotional responses. People that want to spread the correct information want people to know and learn. Two completely different end goals. Not only that, it takes significantly more time and energy to explain why some bullshit is bullshit, than it takes to just spread it.

Put it another way, disinformation is a machinegun and trying to fight it with more speech, like fact checking, is wearing a bulletproof vest. It's better to make sure no shots are fired than praying it doesn't hit an uncovered spot.