that depends.Doesn't matter. APIs change for a reason, and therefore isn't Apple's fault, but WD's for not staying up to date with Mavericks and API changes.
is WD claiming that their software is supported and compatible with OSx Mavericks?
or are people just using the software, and assuming that because it worked for ML, it'll work for Mavericks?
it its the 2nd, and people are assuming, than it's their own damn fault. if the product literature doesn't explicitly say "Mavericks" or "10.9" on its compatibility ilist, it is actually neither Apples nor WD's fault in the matter, but the user for not ensuring their using the appropriate software.