As we've been working through themes in the theme-experiments repository, a few of us have quickly run into the fact that Gutenberg currently can't render semantic tags like <header>, <section>, <aside>, and <footer>.

Functionally, these would probably just be Group blocks but with different markup: they're just a place to put other blocks. So perhaps this would be some sort of option for that block, only available in full-site editing? Or maybe there's some way we can automate this to avoid confusion for users?