Because when your account is hacked, then they can claim that you are responsible (or) at least partially responsible, and not offer to re-fund your account. Go ahead and sue us, we have lawyers on salary, you have to pay out of pocket for yours, the same as for all big corporations who treat consumers unfairly.
Years ago it was claimed by some that a famous anti-virus "celebrity" had backroom deals with hackers to hack big corporate accounts so his firm would get called in for the recovery operation.
Senators Elizabeth Warren and others held hearings and brought big bank officers in to testify, who mostly just acted aloof and uninformed:
https://www.warren.senate.gov/oversight/reports/new-report-b...
Until class action suits are brought, nothing happens, and even then the lawyers and the big corporations too often just negotiate a deal where the lawyers get paid $$$ millions while the consumers-victims get like a $10 rebate coupon.
This is unfair. I have gotten settlement checks for as much as $15 US Dollars. I have never gotten a coupon.