If you set an area to have a maxComponents property then when that area has reached its max it should cause the "+ Add Component" action to be disabled/removed when that area has the focus.
Steps to recreate:
1. In template defs configure stkArticle base area to have a max of 2 components
2. Edit the base area of /demo-project/about/subsection-articles/article
3. Add 2 components
4. Observe the max message is showing but you still have the ability to execute the add component action.
The system still prevents the third component from being added but not until the save button is pushed in the dialog. A warning is is logged but there is no indication to the user that something has been restricted.