There are some things which it's impolite to say, in any words, because the sentiment is impolite--for example, "I don't want you to come to my party." Guess culture, applied well, allows you to avoid having to say those things or cause the attendant hurt feelings. (Guess culture applied poorly avoids the hurt feelings but puts you in the awkward position where they're at the party anyway because you felt compelled to invite them.) The same situation in ask culture requires you come out with it.

This may sound like a good thing in the long run--especially if you are yourself asky--but sometimes there are valid reasons both that you don't want someone at the party (they smell bad) and that you don't want to hurt their feelings (they're your boss/family member/other person you'll be spending more time around, especially in a position of authority).

Another thing guess culture is good at is keeping secrets. In ask culture, if someone asks you something you've promised not to tell, it's certainly valid to say "Sorry, I can't tell you." But then they know there's a secret, and sometimes that alone is enough to cause harm--through speculation and deduction, or asking someone else, for example. (You could also lie, but that might cause its own problems.) In guess culture, there are things you don't ask about. This is part of why.