Spitty. I will explain.
It is not because of the pushrods or any such thing that OHV pushrod engines make more torque, it's simple flow dynamics. On non VVT engines, meaning conventional static valve timing only, pushrod motors are predominantly 2-valve per cyl.
Having 2 valves instead of 4 means less air flow when the engine is revving high for a given engine size, but it also means higher air velocity when the engine is at a lower RPM. The flow dynamics of a 2-valve head lead to it having better low-end than high on conventional cam designs from factory (the ones the idle smoothly).
Now, that in mind, the same thing can be achieved with a SOHC design using 2 valves, but eliminating the pushrods. Furthermore, DOHC can benefit from using variable valve timing and lift to give it better low-end flow without killing the high-end flow capabilities.
In the end, a properly built DOHC with variable valve timing and lift, or **** variable cam timing, is going to be the BEST possible outcome. However, for most non-performance say truck engines, a nice mechanical no brainer cheap to make pushrod engine works just dandy.
Does that help? I have links if it doesn't.