You can drop the first two. And the third can have different motivations: I think here we just have a mathematician with sufficient time on their hands who enjoyed coming up with this. I think the primary valid complaint is: overly complex for its task.
it's not just overly complex, the use of 'dependent types' for this indicates that the author doesn't understand how they are really useful. neither he seems to know what serialization is, he apparently wants to serialize linked lists.