Sure, but the web is a unique portability story in the history of computing. Has any other platform been an open standard that ends up being table stakes for any new entrant? Think about it, if you try to make a computer without a web browser today, you'd be laughed out of the market.
Number of machines that can run code written in the language isn't really the best metric for realistic portability. Sure, your toaster might run C and not JS, but it isn't going on run your C anyway.
My browser isn't running my JavaScript, it's running yours. In fact, the capability to run my own code in my own browser is being slowly but systematically removed from the browser.
When I said "you" I meant "the developer" not "the user": the class of devices that run C and not JS is also a class of devices that generally don't run third party code. If you aren't a hardware manufacturer (or trying to sell middleware to one) the fact the embedded systems run binaries that were programmed in C isn't in any way relevant.
