It seems the Ask culture's norm is more favorable in welcoming new members whereas the Guess culture's norm is more favorable in building loyalties to the community among members. IMO curiosity and fear are underlying factors of the cultural differences.
An interesting thought exercise is when Ask people somehow happen to live in a Guess culture. It's like all the guess culture members are working with their own cryptography that's not allowed to the newcomer, and when the new person asks for the code, no one can clearly give the code to the newcomer. The code has to be learned by spending enough time with the community members.
Language is one such barrier -- unless you learn it at an early age, it is sometimes almost impossible to master the intricacies of a language. There are also other numerous cultural aspects that take time and effort to learn, which helps the coherence and integrity of the "guess" culture members.
But even in those Guess cultures, there are also people with curiosity and willingness to learn new cultures, which could move the cultures toward the Ask cultures. That's at least what I learned while I studied the 19th and 20th century history of Korea and Japan. They are not always successful in making changes and progresses within the society, but when they do or when the changes come, they are those thriving, by asking questions about the new world and the new norms. IMO this curiosity is the catalyst for the change from a more Guess culture toward a more Ask culture.
On the other hand, there's fear, the fear of the newcomers. IMO that's what drives the Guess culture, and also another powerful motivation that moves a culture toward more "Guess" culture. In US or European politics, you see all these nationalistic movements. As one of the comments said, even in US, the Guess culture is more predominant in the locations where the fear against other ethnic groups is dominant. It's just the correlations, but IMO there's some feedback loop between the fear and the Guess cultures.
In the end, it's easy to see why the Ask cultures would become more dominant: Ask cultures can easily talk to each other and learn from each other, while Guess cultures are exclusive even among themselves, which make them more difficult to learn from others.