[happytoexplain]

The grandparent's assertion was in the general case, not specific cases. However, even for your specific cases, it is possible - even likely - to at some point handle user-facing text (i.e. text that is reasonable to localize), at the very least in the form of error messages. Also, the complexity of Unicode is typically already well implemented by default in most environments, and the real issue only comes at the intersection of user-facing text and functional strings (e.g. URLs and filenames), which is a problem that Unicode is another tool to exploit, but not a problem that Unicode invented. We have been trying to detangle the dual nature of URLs/filenames for a long time.

However, tangential to the grandparent's topic, I do imagine there are very specialized cases where Unicode is pretty objectively unnecessary.