Depends on the BJJ school. Some are more proscriptive than others. Regarding flexibility you are confused. Many people have advanced the BJJ game to where it is today which is far beyond the levels of competition you saw in the 1990s. Eduardo Telles is one of those - not a "whacko", but TT (Eduardo Telles & Terere) were one of the top competition teams in Brazil for many years. Telles innovative work is the turtle position - legit stuff form there. There are many others like him though - Delariva, MG, Mendes bros, Robson Moura, Eddie Bravo. All the Sambo footlocks get absorbed and integrated. Wrestling gets absorbed, integrated, taught. All the advancements are because people are able to test it in a competitive environment to see what works.
You are clueless. Most BJJ schools teach wrestling as the standup portion of nogi grappling, and judo as the standup portion of gi grappling. But it is entertaining listening to you go on about BJJ, which you know even less about than WCK.Nobody would argue that wrestling is a better approach for fighting on the ground than bjj