The distributions publish their own configs, and certainly this is the sanest place to start, although even paring down the hardware can take a bit of time. (now building video4linux will save you alot of compile time) And if you pare down the wrong thing, your resulting kernel won't boot. This last part is what the proposal is meant to address, to prevent from removing features that are 100% required by the user-space you are going to boot. The kernel already has this concept for some drivers and features (CONFIG_EXPERT).
The biggest problem I see with this, is that, 1. for distributions like Debian, this type of definition doesn't really exist, as core things like init system are swappable. and 2. often the software that requires these things doesn't really know it requires these things.
I've submitted patches making systemd a little better when it comes to kernels with slightly less that the Cadillac model of configs. (these were in non-essential helper programs, the system still worked fine)