In context of this article (at least), Sekizai is useless. You've been able to do this out-of-the-box with Django for a very long time. You can always reference inherited content in a Django block with {{ block.super }}. This feature has been around since AT LEAST v1.1. That's when I found the feature.
author of sekizai here. you seem to misunderstand what sekizai does. it's not a replacement for block.super. it's main points are support for included templates, for loops and being able to put content anywhere in the template from anywhere. It is however entirely possible that you have no use case for it, but dismissing it as useless is a bit harsh in my opinion.
