I believe this started with the European competitive fly fishing community. But has since spread to Euro style nymph fishers and nymph fishers in general around the world. A competition style jig fly is simply a fly tied with a large tungsten bead so that the hook point rides upward.
There are competition style jig hooks available which have a 60 degree bend at the eye, generally a wide hook gap, and generally a barbless point. See, for example, the Tiemco C400BL.
Competition style flies are generally impressionistic with a "hot spot" either at the tag or the collar. Many are tied "in the round" and many are tied with hard body materials to facilitate sink rate.
If you object to weighted nymph fishing, then they aren't for you. Otherwise, they are just a modern refinement of nymph fly design that have some advantages.
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