I agree that these are annoying for developer and somewhat harmful for traffic. However the real problem lies in politics. When browser representatives suggest a new standard and everyone says "fine, we like it but we must think about it" it makes sense to implement this standard in vendor specific way. That serves as a live example for all developers, standards committee and developers of other browsers, yet nobody can blame them for implementing new standard cowboy style and trying to get it become de-facto before everyone has agreed like MS use(d?) to do. The question is "when should the vendor prefix go?" Obviously right now it's happening too slowly so maybe the whole process needs to be improved and maybe there needs to be a mid-state for new standards - one that is not "in-draft" and not complete either ("release candidate", ha!).