And if it's noticed, it's in the form of corrupt or missing files... much fun is had by all.
But people say the same thing about God(s). God(s) didn't invent all these human inventions, so it's up to be corporate responsible since they want corporate personhood. Unless Persephone and her buddy, Centeocihuatl the Corn God, created all this tech when they got bored once the harvest was over... Which goes back to the core question, why Apple dumped ZFS, won't make compression in HFS easily accessible (compression feature was added in 10.6), etc...)
Apple seems to have dumped ZFS over licensing issues: http://arstechnica.com/apple/2009/10/apple-abandons-zfs-on-mac-os-x-project-over-licensing-issues/