It was just idle curiosity - I wasn't familiar with the term "static class", looked it up and wondered if that particular set of features (and the term) were used in any other languages.
Nothing special about it, it was just a cheap feature to add (static was already reserved and not previously added before class) while helping to exemplify a common protocol.
The one nice thing it does provide is access to defining extension methods, which aren't allowed outside static classes.
