I think you are missing my point. Bandwidth throttling is only one of the tools you need for performance testing. You may also need to, say, change the screen

I think you are missing my point. Bandwidth throttling is only one of the tools you need for performance testing. You may also need to, say, change the screen size and reported device resolution and user agent at the same time. Chrome gathers all these tools and tons more under the same page. And they are specifically created for this purpose, hence probably more accurate than some OS specific implementation.