I have not heard that trucks are less capable than SUVS, but I am not an expert. I do know that we towed first with a Pathfinder SUV and then switched to a Tacoma, and the Tacoma has out-performed the SUV. I don't know if it is a fair comparison.
But we go off road a lot, into snow, mud, ice, and sand, and the Tacoma has steadily pulled the trailer into (and better yet, out of!) some tough situations. When the going gets really bad, I put it into 4 wheel low and grind my way through.
I should also add that the Tacoma pulled the fully loaded trailer (including full water tank) up a 26 percent incline a couple of years ago. That is not a typo -- this was the east side of Sonora Pass. The sign said "not recommended for trailers." I had talked to the Calif Hwy Patrol office in charge of that road and described my setup. They said, "no problem, you are good to go."