Not a myth. Perhaps a silly rule. But the infinitive in English is real, a verbal, that is, something formed from a verb, but which functions not as a verb. "To go" functions as an adjective or noun. "Its five year mission is [x]." You could fill that in with one word, like "peace" or "fun." Or with an infinitive like "to go."
It isn't a myth, it's a verbal (as are gerunds, like "going" in the sentence, "Going is nice.")
As you can see at the start of this post, I break rules in my informal writing, but the infinitive is a real thing. Splitting it might be fine, but it does exist, just not in the one-word, Latinate version. Someone above asked who even knows about them. We are here. And we are among you.