I had always assumed that;

1.  The TRF set is essentially a Superhet IF.
2.  The TRF has some major disadvantages for multiband sets, like the big clunky coils of my RU receiver 
3.  The TRF had to cost more to build than the Superhet, given that complex tuning mechanism.
4.  Hence the Superhet.

Now, since they used CW a great deal in those thrilling days of yesteryear, how did they receive it on a TRF set?

Wayne
WB5WSV