B-52s references aside, I think one main reason people don’t win with Behemoth more often is because they don’t know how to use Rock Wall most effectively. I found it to be a powerful tool in Hunt, because I’ve utilized it in one way that maybe some people have discovered, or not, I don’t know: to defend yourself from attacks when wailing on the Power Relay.
On more than one occasion, in order to win the game as Behemoth against (who I perceive to be) expert players, I’ve used the Rock Wall to shield myself from damage while I mash on the Power Relay. If you place it just right, you’ll basically get free damage on the Relay as the hunters either have to go around or wait for it to come down. If they happen to be split up, well, you’ll only have to deal with the split hunters anyway as you can basically use the Relay as a…second wall, I guess? So you’re not flanked? I hope that makes sense. And if they happen to have Cabot, well, Rock Wall is still useful in this regard as Cabot doesn’t have a clear shot. (Unless you’re dust-tagged.)
I’ve won more than one match using this tactic. I know when I was on @MaddCow 's stream earlier he wondered why I put so many points into Rock Wall. It’s because Rock Wall is more useful than one might think, at least in Hunt. Arena, maybe not so much, but in there I picked it high because of force of habit. It helped me get to Stage 3 in the Arena, at any rate, and @MaddCow can vouch for that.
If anyone wants video of me using the tactic I described to destroy the Relay, I can make one, as I captured footage of me doing so. I just gotta put it together.