This is my last attempt
ALL vehicles have engine choices, most cars have 4 and six banger options, some have 4, 6, or 8 as options. I see that we can agree on this.
Fullsize trucks are the same. They typically offer a V-6, "Base V-8", a more powerful V-8, and towing packages in all sorts of configurations. The previous Tundra's lack of the "higher power" V-8 and competitive tow ratings (when compared to the higher end V-8's) were what gave it the "7/8" "nickname." True, it's base V-8 and V-6's were COMPARABLE to other trucks V-6's and base V-8's, but that's where the comparison's ended. It didn't have an engine that gave it the extra oomph to be competitive with the other higher end V-8's. That's why they were never considered "true" fullsize trucks.
I was being sarcastic about the ford engine