I wouldn’t say that, it’s just there is a lot in vendor kernels and little incentive to upstream stuff for older SoCs that have already shipped. It’s true Google has come around to the importance of not drifting too far from upstream and hopefully we are starting to see the results of that change in attitude.
As I understand it my colleges in the QC landing team @ Linaro spend a lot of time getting stuff into the various upstreams.