Credit cards are zero liability anyways, even if you notice the fraudulent charges months after they occur. Debit cards aren't so forgiving.
I use one Visa, one Amex, one Discover, and one Mastercard online for a variety of reasons (Amex on electronics for bonus year of warranty for free, Discover for cashback on many sites, up to 20% on accessories from Dell sometimes - you can get 20% on a new video game at retail price - etc.), plus the cardholder exclusive discounts/usage scenarios (no, we don't take Amex here, etc.).
Never lost a credit card number online to a scammer
IRS did lose a laptop with my tax documents on it. Got a year of Equifax credit monitoring. That was it. No new SSN, not even monitoring from the three bureaus- one year of monitoring. Yipee! Oh, and an apology, but no explanation as to the measures taken to ensure it doesn't happen again rather than your usual PR babble.