Because the US credit system requires you to do it this way, also since their card safety is dogshit you want credit in case someone skims your card, because it's not your money being stolen (it's easier not to pay the CC company than getting your money back from someone).

Another reason is that a CC usually allows higher offline transaction limits, which might be valuable for some.

Just because your direct debit scheme makes sense to you doesn't mean it makes sense for EVERYONE.

I have a VISA debit card and a Mastercard CC. I use debit the most (commonplace in Sweden) but keep the CC around as an extra if my bank has downtime or if I'm traveling the less connected parts of the world.

Widen your views, things are different all over the world. Imagine billions of people don't have access to the internet and you'll find that your way isn't the only way, in some places they pay with sex, food, cattle, cash, CC, direct debit, crypto, futures or whatever convoluted (in my opinion) system they can come up with.

If you're in an AMUSEMENT PARK or A BATHHOUSE you might transact with a tag and pay when you leave.