The 1.0 beta milestone does not mean Gutenberg is complete. It is an milestone that means Gutenberg contains the features we've deemed are necessary to address the editor focus kickoff goal:

The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.

https://make.wordpress.org/core/2017/01/04/focus-tech-and-design-leads/