In reply to William Earnhardt.

It’s been available to activate on wp.com ever since the Try Gutenberg callout was included in 4.9.8.

It's only available to users who use wp-admin. It's not available to Calyspo users - ie, the default WP.com dashboard a majority of WP.com users use.

Automattic is using WordPress core as a test bed for WP.com.

I think part of the reason for this is due to apathy outside Automattic for Calyspo.

Automattic's idea for Calyspo was that they'd develop it internally, get buy-in from plugin developers, then
merge it with core.

That hasn't really worked out, plugin authors haven't embraced Calyspo - their customers aren't asking for it.

Matt seems to have decided to flip that development process around as a result of that experience - do it in core first; it puts more pressure on the plugin developers and the community to support it than doing it on WP.com first would.