Here’s what I do which simulates your Read All New button:
Like most of the @team member, I read all of the topics/posts here. Here’s my morning routine
- Go to https://meta.discourse.org
- Click the first unread/new topic (sometimes it’s random, sometimes it’s the first that catch my interest)
- Press j to go down the topic as I read the posts
- Once I’ve reached the end of the topic, pressing j again will select the first Suggested Topics (which prioritise unread/new topics)
- Press o to open that topic, which will go to the latest unread post of that topic
- Repeat steps 3-5 until I’ve read everything
Often I press l to 
a post.
Sometimes I press b to 
the currently selected post or f to the whole topic ("f" stands for favorite)
Sometimes I press r to reply to the currently selected post.
The combination of Suggested Topics and keyboard shortcuts makes it really easy and super fast to Read All New 