I think we've lost sight of one of Gutenberg's primary objectives. Per Matt M, "The overall goal is to simplify the first-time user experience of WordPress..." https://ma.tt/2018/11/a-gutenberg-faq/

As a website designer who works with clients all day, every day, I can tell you that the Block Editor is already over-featured, confusing and frustrating for the average user. All they want is to be able to add content quickly and easily.

Expanding the Block Editor to being a full-site editor is downright scary. We will need to restrict access to blocks based on user role -- with authors and editors only able to use a subset of block types to prevent them from breaking the website.

Perhaps it is more logical to restrict access to blocks based on post type. Pages are typically built by designers or power users who will need the full set of block types. Posts are created by less-expert authors and expected to conform to a standard template where they share the same look-and-feel. For these, there will be many blocks that should not be used. And for custom post types (for example, events, jobs, documents...), similar block-type restrictions would be desirable in the real world.

I'm praying that that we don't do what Mary from London is proposing. Adding an option for every CSS option (line-height in her example) will create an unwieldy user-interface, further complicating the post creation and editing process. That would transform the Block Editor into the likes of Elementor, Divi or any of the other mega-themes, which are beyond the skill set of the average user. Every option we add makes the block editor more complicated and potentially makes authors and editors less productive.

Let's not lose sight of the original objective to make the block editor simple to use.