I need to call out a myth about UTF-8. Tools built to assume UTF-8 are not backwards compatible with ASCII. An encoding INCLUDES but also EXCLUDES. When a tool is set to use UTF-8, it will process an ASCII stream, but it will not filter out non-ASCII.

I still use some tools that assume ASCII input. For many years now, Linux tools have been removing the ability to specify default ASCII, leaving UTF-8 as the only relevant choice. This has caused me extra work, because if the data processing chain goes through these tools, I have to manually inspect the data for non-ASCII noise that has been introduced. I mostly use those older tools on Windows now, because most Windows tools still allow you to set default ASCII.