Ford engine designers, like many others (including International Harvester trucks) used a nested main bearing cap design. This uses the side walls of the nest, to stabilize the bearing cap, and it is more able to resist any force applied from the crankshaft.

If a crankshaft is spinning at 6000 rpm or more, and the vehicle abruptly changes direction (as in road racing, or boat racing in rough water) then the crankshaft is actually like a gyroscope and it wants to remain in position as it is moved out of position. That puts a LOT of force on the bearing caps, thus the nested design. Without the nested design, the bolts that extend through the caps would take ALL the force, and if that had been tried in the past, I’m sure they learned the hard way that it wasn’t too good an idea.