Japan has a pretty strong local tech industry. Microsoft Word needed to add all kinds of features, including both vertical writing and weirder stuff like a dict

Japan has a pretty strong local tech industry. Microsoft Word needed to add all kinds of features, including both vertical writing and weirder stuff like a dictionary of seasonal greeting phrases to use in formal correspondence (https://learn.microsoft.com/en-us/archive/blogs/office_global_experience/special-east-asian-features-in-office-2010#japanese-greetings https://learn.microsoft.com/en-us/archive/blogs/office_globa...) to compete successfully with Japanese word processors. So I suspect the causality is the other way around; there wasn't much demand for vertical form controls for the same reason you don't write emails in cursive.