We added the full width option to blocks because it provides a way to implement the new page headers of the IA project.

There's some things we can improve about this new functionality that were not taken up to ensure the block could be delivered in time.

• Image blocks are supposed to stretch to full width, but don't because of some of our CSS.
• On regular posts we maybe don't want this option, but by default WordPress only allows to easily set this up on all post types.