I sell cranks and crank related tools for a living and the answer is simple.

Fast strong riders want the large chainrings of a road crank and mere humans need the small rings of a mountain bike crank. Road triple derailleurs will work sorta OK on MTB rings but not the other way around. I've sold about 150 shortened Octalink 105 and Ultegra road triples and about 1/3 have had me upgrade the rings to 24-39-48.

Modern road triples have recently gone from 30-42-52 to 30-39-52. Some of the newer triple road derailleurs won't even work with less than 12t difference between middle and large ring. Modern MTB cranks are almost all 22-32-44 - 4 bolt on 64/104mm BCDs.

The ideal touring setup for most people seems to be 24-36-46 but YMMV. Hardly anyone sells a nice 74/110 road triple anymore. Sugino sells the XD-600 with 26-36-46. The customer requested replacing the 26 with a 24 on almost every one I've ever sold.

Older 74/110 MTB triples are an excellent choice for a road bike for the average rider. With 11 or 12 small cogs very few of us need larger than 46t. I still use Suntour freewheels with 14t small cogs and 46t or even 42t is plenty for me.