This is such an apples-to-oranges comparison that I can't really see how you'd come to that conclusion unless you were already biased against Rust/LLVM/Firefox

This is such an apples-to-oranges comparison that I can't really see how you'd come to that conclusion unless you were already biased against Rust/LLVM/Firefox coming into it. Mozilla is against all browsers, i.e. every single piece of software that can be used to connect to the world-wide web--the most important and influential piece of technology in the last half century, being based on the same codebase. The fact that a browser is compiled by a single compiler is absolutely meaningless, because it still provides another option over other compilers. This doesn't have any bearing on the browser monoculture, and it has no bearing on C++/gcc's feasibility because there are still a thousand other compilers and projects not affected by this. The fact that Rust only works in one compiler is also pretty meaningless because that's not the problem Firefox set out to fix. And say Mozilla did care about what compiler they were using because it locks them into one of them. They would go ahead and develop a new alternative Rust compiler with an alternative backend. Oh no! They're all using Glibc still! And GTK+! And the X.org monoculture!!! The current goal behind Firefox is to provide an alternate browser that isn't based on Webkit, not to make sure that every piece of software is equally competitive.