I may be misinterpreting the end result here, but... in the first conversion example Fränk provides he poses the question, "why do I need this tag?", in relation to the HEADER landmark element. He decides to conceptually reduce the HEADER tag to being "a container" and replaces it with a DIV.

This is obviously disappointing for a11y reasons, but the immediate issue is this sets a terrible precedent when it's likely these early FSE themes in the directory will become a model for others to follow.

*sorry for ALLCAPS above, not sure if/how HTML tags can be added in comments here.