It's an interesting question, Ros. I think I'll move this from WikiTree Tech to Policy & Style.
I don't like inconsistencies like this, but sometimes they're appropriate. The original logic: A newer member might be intimidated by something that says "Biography" and would hesitate to enter anything there. More experienced members know that random notes are OK. This is a wiki. Biographies are meant to evolve significantly over time. More experienced members also know that the notes are going in the Biography section.