Because, as jinjuku and I have pointed out, your FICO score is used for a lot more than you apparently think.
No one will take a little time. Like your insurance company. No insurance company I've ever heard of writes a policy the old-fashioned way. You've already admitted you think you pay on the order of $30/month more for insurance. I get your off-the-grid attitude, but your philosophy is not a good model for people to maximize benefits from the US financial system. It's just your preference.
That's the entire point. Debits cards have no buffer from bad actors. Either do checks. I'm aware of the federal consumer protections for debit cards, but they aren't as safe exactly because they give merchants the ability to get funds from your checking account directly. Basically, they're never safer, unless you can't control yourself. Read all about it:
Learn why credit cards are safer to use than debit cards. Plus review the fraud protections for each and how to protect yourself from fraud.
www.experian.com
And, since most products and services are priced exactly the same for credit and cash customers, by not taking advantage of credit card cash back policies cash/check/debit card users are effectively subsidizing credit card users. Thank you.
I don't know what to say. If you were a computing peripheral device you'd be a printer. Output only. My comment wasn't advocating you use debt, only that a good FICO score has benefits beyond credit worthiness. You've got this off-the-grid financial attitude going, and you're saying you're successful
because you did that (your emphasis). You can be successful just by not buying things you can't afford and living below your means, and I would add investing and saving. This financial cult you've cooked up for yourself is fun to read, but difficult to advocate when examining the facts.
Are you saying jinjuku and I have no control over our money, because we use credit cards?