[yossarian19]

Depends what you mean by diagonal link.
If you mean a triangulated 4 link, yes - sure. The only reason I'm aware of that they aren't used more commonly is it's harder to get the geometry right and harder to package the thing on a chassis and on the axle. In the 4x4 crowd the dual-triangulated 4 link is King - it needs no panhard bar and can flex quite a lot if set up correctly.
For street rods, the suspension travel is usually pretty small and a parallel 4 link + pan hard bar works just smashingly, and is easier to design + package + sell + install. For suspension articulation, not so much - but then, not many people on this board are in it for the rock crawling.