I am trad and I don't need to know how WFP works, so why does a WFP WC need to know how trad works. If he's built his round just doing WFP, then fine. If a customer asks, can you do the insides and he says no, then I don't think his business is going to crumble. There is loads of work out there, where only the outsides have to be done.
If there was going to be a hose pipe ban, then I don't know what WFP guys would do.
For me, trad is important, because a lot of our customers want the insides done and they pay good money for it.