The word limited used to be a compliment. It meant limited and exclusive service, like limited to pullman passengers. Or limited stops. It was especailly used in the days of heavyweight trains. The trains with "limited" in their names were the faster and more exclusive trains. in the heavyweight era. In the streamlined era, sort of in the late 30's, on a small scale, more in the late 40's, the new trains for some reason usually were not called Limited. Somehow the term "limited" sort of got pushed back and lost its original emphasis.
Strangely, a train called "limited" began to be one not so hot. The streamlienrs had theirs names like Super Chief, CZ, etc.
Today, after all this, the term truly means nothing at all.
Illustrative of the above, the Crescent , for example, was originally called the Crescent Limited when it was begun in 1926 or so. When it was streamlined in 1949-50, the name "limited" was dropped, a good way of siignifying that the word was rapidly losing its original mystique.