We have and hear them often but they don’t come in handy. Also, they are easier to challenge than accept.
The reason being that, more often than none, they challenge the things we know and believe in. As such, these thoughts call for strong scrutiny.
As much as we love to hear and carry plausible ideas, they can be our undoing if we let the lethal ones pass through the ‘thought filters’ of our subconscious mind.