Regardless of whether or not this was unnecessary after the last one was produced in 1912 - 20+ years prior to the implementation of the "New Deal"...
"The problem was that it cost too much to build."
I have several pictures of the 6-wheel ELF driven by Depailler in 1976 at Mosport.
Would like to post the photos if there is a way to do so? OK figured it out. Here they are.