BFS vs. mainline scheduler benchmarks and measurements

Well, I'm a counterexample: I upgrade my hardware every decade, if that, but the kernels are normally as new as possible, because I'd like newish software, thanks, and that often likes new kernels. Further, everyone I know who isn't made of money and runs Linux does the same thing: they tend to run Fedora, recentish Ubuntu, or Debian testing, because non-enterprise users generally do not want to run enterprise distros because all the software on them is ancient, and non-enterprise distro kernels *do* get upgraded.

I suspect your argument is pretty much only true for corporate uses of Linux (i.e. 'just work with *this* set of software', as opposed to other uses which often involve installation of new stuff). But perhaps those are the only uses that matter to you...