For offline support! Chip cards were introduced before internet connections were ubiquitous.

Some cards were even explicitly offline-preferring as long as there was any offline balance remaining to save on data transmission and processing bills.

There are even some fully offline chip systems around (where both terminal and card are mostly offline) that take the “offline purse” idea even further, but these are usually separate from the mostly account-based debit and credit schemes popular today, and are often getting phased out.

These days, cards are mostly online-preferring or even online only, with some merchants taking on the risk of accepting cards while offline.