To be fair, all of those started as FOSS outside of Apple. LLVM came from academics at UofI, CUPS has been around since forever and they just bought it and star

To be fair, all of those started as FOSS outside of Apple. LLVM came from academics at UofI, CUPS has been around since forever and they just bought it and started paying the main dev, Darwin came from pillaging NeXT, and Webkit famously was based on KHTML from KDE.