Chip and PIN cards can support tokenization, which prevents the merchant (or anyone who has hacked the merchant) from seeing the card number, but they are not required to do so. I haven't seen any numbers on what fraction of cards use tokenization.
Something to keep in mind is that when chip and PIN was developed to combat credit card fraud it was card present fraud that was the big problem, either by someone using the stolen card itself at a brick and mortar merchant or making a counterfeit cart by writing the stolen number onto a blank card and using that at a brick and mortar merchant. Card not present fraud, where the number is used but not a card such as at an online merchant or a mail order merchant or telephone order merchant, was much less common.
Chip and pin made card present fraud much harder because it was much harder to obtain blank chip cards and the equipment to write a stolen number to them, and it made using an actual stolen card harder because of the PIN.
Something to keep in mind is that when chip and PIN was developed to combat credit card fraud it was card present fraud that was the big problem, either by someone using the stolen card itself at a brick and mortar merchant or making a counterfeit cart by writing the stolen number onto a blank card and using that at a brick and mortar merchant. Card not present fraud, where the number is used but not a card such as at an online merchant or a mail order merchant or telephone order merchant, was much less common.
Chip and pin made card present fraud much harder because it was much harder to obtain blank chip cards and the equipment to write a stolen number to them, and it made using an actual stolen card harder because of the PIN.