This model would never have come about except due to the way the Linux kernel is developed, with multiple developer helping each other out, and forcing developers to break their changes up into small individual pieces. Combined with the fact that all device drivers are within the kernel source tree, this has enabled Linux drivers to be, on average, 1/3 smaller than drivers for other operating systems.
Portions of this model have now been copied by the BSD kernels, including MacOS, validating the basic idea in a cross-codebase manner.