Don't know which features of the Linux kernel OP expects to be of importance to developers, but (historic perhaps) to us it (painfully) mattered that Linux kern

Don't know which features of the Linux kernel OP expects to be of importance to developers, but (historic perhaps) to us it (painfully) mattered that Linux kernels before 3.10 didn't support docker fully. Every now and then, there is a feature that matters to userland.