If you're on a platform where Kindle Reader app is available, is there any reason to use the Kindle Cloud Reader? I guess there are some people who buy Kindle

If you're on a platform where Kindle Reader app is available, is there any reason to use the Kindle Cloud Reader? I guess there are some people who buy Kindle books but whose main OS is ChromeOS (like the screenshot in the article) or desktop Linux. What's the solution for them? Use ARC (Android Runtime for Chrome)?