That's the thing, the manufacturer can rate the cells at any C they want. The real question isn't whether these are "rated" for 10C, but how much degregation these will show after 1000 cycles at 10C. Cooling systems will also play into this: If we assume 5% charging losses that's 50kW that will need to be dissipated while charging for the cells not to heat up - no small feat even if the losses are lower.