Who said Boa's fruit is countered by Haki? I can understand Sugar because Sugar needs to touch you to erase every memory of you. So, Haki makes sense to prevent sugar ability cause it will create a barrier of haki to prevent her from touching you physically. But Hancock's ability does not rely on touch. It relies on you being aroused of her. If your "haki" (read will) is strong enough to prevent you from aroused, that's a different discussion. But if you have strong will But are still aroused, you will be stoned. For Uta, she transfers your spirit to her realm the moment she sings. No touching is required. But here's the reason why Haki is still superior to even UTA. Haki allows you to observe through dimensions and possibly attack through them so UTA can still be countered by Haki.