having worked on AOSP for 3 years. I can attest most developers are capable but are not incentivized correctly. The appearance of improvement (demo quality code) is good enough in many circles to "complete" a project and move on. Net effect - the tragedy of the commons. Compound over a decade and 10-20 minute builds and 5-10 minute test time is the norm, and at that point even properly motivated - "would die for clean code" - sort of devs have a hard time. Put in place completing management chains all behaving the same (want to appear more productive/useful than others) and the mess is very hard to get out of. People were allowed/encouraged to cut corners I would let a junior dev cut on any project (duplicating resources from different parts of the build), building tool that demanded duplicate configuration, etc. Not a problem of capability (in some cases, yes, but rare), a broken selfish set of senior devs and leadership. Likely because it's not in google's interests for the project to be easy to work with/productive on. Open source washing was useful early on, now it's something of a liability. Only data gathered from devices and a little bit of cash from the play store are assets.