The kernel also still plays a vital and security-meaningful role in processing calls from applications.
Running an out of date kernel could mean strangers ransoming your data, or could mean an attack becomes persistent and starts logging and uploading through reboots.
Running an out of date kernel often does not result in this, and that higher level security matters first.
However, the kernel does have an attack surface through those higher levels, and pwning the kernel still means something.
Those datacenters are running LTS kernels with minor versions updated, or have security patches backported, or have far more limited connections to the world than your phone — only one protocol, one port, one service, for example.
One example, since you asked: https://thehackernews.com/2019/10/android-kernel-vulnerabili...
