I think people just shouldn't generalize. Strong Haki is effective in countering DF Hax. But apart from that, if we take an elemental power for example, while strong Haki can solidify Logias or maybe even interfere with their usage, you cannot nullify their effects. Like, if a magma fist blows a hole in you, Haki won't magically regenerate it. If Aokiji freezes you to the core, you cannot dispel the ice with Haki, since you became a chunk of ice and lost consciousness. Being frozen is just the result of the power, not the power in action.