This looks neat, but even after reading their FAQ I don't understand the namesake feature -- why or when would I need more than one; and in that case, why is it

This looks neat, but even after reading their FAQ I don't understand the namesake feature -- why or when would I need more than one; and in that case, why is it a benefit that they snap together? I mean, is it just because it looks tidy/neat or is there a user story where this has additional value?