Possibly, but I go to British coin shows and you'll not see any sign of it If they are doing any business in Britain it is not with mainstream buyers and sellers. And don't China make their own PCGS holders for their homemade coins?
So no slabbed coins whatsoever? that makes things a lot simpler for a seller. Simpler and cheaper for both buyer and seller. The wise buyer does not go charging off spending large sums of money unless they know what they are doing, the wise seller does not overgrade or overprice, but of course, there are plenty who will do both. They just don't sell much.