The proof was actually written in Laconic, and then compiled down to a TM. We already know certain things about TMs (like busy beaver and the halting problem) so you don&#x27;t have to re-prove those things about your new machine if you can just prove that it&#x27;s equivalent to a TM. It&#x27;s mainly used as a convenient way to keep score. If some other proof can be proven equivalent to a TM with fewer states, then you have a better upper bound.