I think that I'm understanding the concept for the need/use of hidden menus. Hopefully when kvo3369 returns this will help them and others hat run into this "article opens in the same page"
Most of the time, if you have a read me button, you would want it to open in the same page as it's the total article. But as in the Demos there are articles/modules on the home page and it messes up things if they go to the top of the home page and open. Thus the need for a hidden menu/link to send them to their own page or a related page.
What helped me the most were these 4 Youtube videos:
https://www.youtube.com/watch?v=x8RrOiMHSg4
https://www.youtube.com/watch?v=PQ9gMRlCiEQ
https://www.youtube.com/watch?v=ZkO-RAz_xSA
https://www.youtube.com/watch?v=GJ33yLG0M_U
When I get lost/stuck I go to Youtube and type in "Joomla tutorial xxxxxxxxx" Usually after 2 or 3 of those, it clicks, maybe for you younger people 1 or 2.