You also can only buy cars from individuals (dealerships run credit checks, even if you pay with cash/check/direct draft) and you probably can't get power, water, gas or Internet in your name (you'd need a roommate and have to pay them).
I was also very surprised to buy a car with cash, only to have a credit check required. It's a real thing. And according to this article, not required, but dealerships are confused by the language of the law and insist on running a credit check, anyway.
The system is rotten and (short of moving country) impossible to avoid.
There is no need to spread misinformation. While it is true that a hard inquiry will have a minor effect on your credit score (less than a 5 point hit), multiple hard credit inquiries from car dealerships or mortgage lenders within a period of 45 days only count as a single inquiry.
You're not at all disadvantaged by taking your business elsewhere, you're just making things up to furnish your dubious story.
That said, going in with a briefcase full of cash is going to cause a lot of other problems.
The dealership wanted to run a credit check if I were to pay with a personal check, but not if I paid with certified funds. I called my bank to have my debit card limit raised to $40,000 for 24 hours and paid for the car on my debit card with no credit check.