Why should I send a message to my relative's mobile phone number when I activate my credit card?

There is a lot of money in the credit card to prevent others from maliciously using our ID card and sending it to their relatives' mobile phones. Besides reminding them that one more person can know, this is also for safety. However, when my credit was activated, I didn't send a message to my relatives' mobile phones. I don't know if it is the individual function of individual banks. The number of short messages sent by the bank is all five digits starting with 9, so the landlord should pay more attention, especially the information such as scammers, to prevent credit card information from leaking.