With all due respect, I would disagree.
A quality car cover can provide a good degree of protection against scratches. And, if your car is washed prior to covering, and your cover is clean, there is absolutely no reason that a cover will scratch it either.
I’ve purchased over a dozen California Car covers over the last few years. Some of them custom tailored for oddball cars. I’ve even had one black car that I had to keep outdoors for two years since I was out of indoor room, and no one believed it was not garage kept. It was spotless.
A car under a quality cover (quality being very important) will stay virtually as clean as when you put it away, even outdoors. And, as long as you wash the car and secure the cover, wind will not damage it. Tarp clamps and rope are your friend in this instance. Tie it under the car in the front, mid-section and rear. And snug it tight.
California covers are pricey but you get what you pay for. They have a cover for most circumstances..
California Car Cover Company - How to Select a Car Cover
All my covers are Ultraweave which can be washed and dried in my home washer and dryer. However, you may want to look at the Plushweave car cover. According to their site.. “Made of 100% cotton fabric, the Plushweave cover has an added pure cotton flannel lining for paint pampering protection. Its ultra dense construction does a superior job of cushioning against scratches and dings.”
Their covers are also "Guaranteed to never scratch or we will refund or exchange your merchandise."