A binary driver
is sufficient if you want to provide a module for a specific release version of a specific Linux distribution. But multiply that single build by the number of different Linux distributions and the number of different supported releases of the Linux distribution and you quickly have a nightmare of different build options on different releases
Considering some of the shoddy drivers I’ve experienced over the years this
developer strategy to drivers makes more sense although I can say that
compiling the Linux kernel these days is long even on faster processors and
getting the source is also not a small task. Although that might be
mainly due to most of the distribution specific build tools that have
surfaced over the years and require learning a new tool to test if it’s
actually better than just make menuconfig for me. In some cases
they are, in quite a few cases it has not.
