With regard to CC playing something of an operational flight deck role in the event of an incapacitation, was it not a member of BA CC who was praised for his handling of the checklist items and generally acting as PNF (including liaising with ATC) on a trans Atlantic sector not so many moons ago. CC had a PPL.
A good friend of mine was former CC and held 757 rating on a CPL. While probably not being up to speed on company SOPs, more than qualified to handle navs rads and checklists.
In at least one other case, I heard of a member of CC getting CPL with type rating, flying a season in the RHS then going back into the cabin as CC at the end of the season. Hardly someone not qualified or capable.
In general though, unless a member of the CC were to fit into something like the profiles above, then I would rather do without the hinderance.
RIX