Ah, whoops. I think we need to clear up what the Storm Hammers do, since I've been picturing drop pods and terminator teleportation. Then again, there's room for terminators in a few places.
>Rad weapons
I think it's a hard on thing. They're one of the cool things about the 30k setting and since every legion has destroyer cadres, they show up. Personally, I think the way destroyer cadres are treated tells us a lot about legions-- are they punishments, honors, the dumping grounds for the weirdos, etc.
It's one of the factors, like the use of tanks and assault squads.
As a result, I think most of these legions have some sort of kill it all and call it a day group. With the Ravens of Morgas, it's specifically about slaying big monsters and the way I imagine them doing that is with nasty rad and chem weapons and massive tempest hammers.
Sarco's Ash Walkers, on the other hand are a heresy Era group dealing with the logic of dreadnoughts and embrace all these weapons along with the flamer, since the flesh is weak.
Sky Serpents Jaguar Warriors use specifically rad-grenades and missiles as a means of crowd control, but it's also because I imagine those as potent tools for dealing with really nasty shit, similar to the Ravens.
Nofr'atos is just the loyal version of Typhus and I figured that a Void Lord was the best fit.
I think the other part of it is that the Oathsworn are a major legion and advise other legions in matters of bioweapons, so they're generally more available.
This said, there's a few examples of big deal Destroyer formations in the OU-- Nemesis Chapter and Dreadwing come to mind most immediately.
Now that you've got me thinking about this and I warn you I am sleep deprived and mildly inebriated, I don't think bio, chem, and rad weapons are universally employed with the same frequency.
>Bloodhounds
>Negators
Probably enjoy hitting things too much
Spears keep it restricted to specialists.
>Paladins
>Knights
Probably too dirty for them