# Why does Travelling Salesman Problem pose the restriction that each vertex can only be visited once?

According to the wiki page of TSP as a graph problem,

It is a minimization problem starting and finishing at a specified vertex after having visited each other vertex exactly once

Then what if a triangle is given, with two edges weighed $1$ and the third weighed $100$,obviously, the shortest path to visit all three vertices are passing the two $1$-weighed edges twice.

So what's the meaning of such a restriction?