Understanding custom dimensions is not that easy. In order to make it a bit more understandable, I took out one example with category pages. It is not that perfect but it will show you the broad idea and how and why custom dimensions can be very powerful if you use them properly with a CSS selector for example. Hope it will help some of you. Do not hesitate to comment if you like it or if you need me to create a specific video about Matomo. Cheers.