Well, yes, but you also need to include vendor x's driver and patches for that thing you have on your embedded system, and you have to consider whether you want

Well, yes, but you also need to include vendor x's driver and patches for that thing you have on your embedded system, and you have to consider whether you want each of the eleventy thousand configuration options. I'm not complaining. IMO it's much easier to build the kernel than to fix whatever bug I'll fix next, and I say that without knowing what that next bug is. Just explaining why it's harder to build the kernel than to add some third-party blah via one or a few lines of Gradle, which may be his basis for comparison.