Yes, USD is the only accepted way of paying taxes in the USA. If you wanna live and consume in the USA, you need to pay tax. If you need to pay tax you need dollars. This is generally how a country ensures demand for their currency.
I can't speak for Cloudflare, but crawling speed should be dictated by the site owner via the robots.txt crawl-delay. [1] A site owner could also rate-limit unauthenticated requests by IP via the cloudflare header using a 429 too many requests error page.