> What a monumental waste of time. Why not just ignore W3C entirely?
Transition costs are probably a factor: as long as the W3C exists and there are web developers who might think it is authoritative, browser vendors will get flack for deviations between browser behavior and W3C specs. If they abandoned W3C that would eventually taper off as people would come to disregard W3C, but it would take time. It's in the browser vendors interest to keep W3C standards as meaningful as possible until W3C gives up entirely, but their involvement makes it less likely that it will be abandoned even if it is largely superfluous.
Transition costs are probably a factor: as long as the W3C exists and there are web developers who might think it is authoritative, browser vendors will get flack for deviations between browser behavior and W3C specs. If they abandoned W3C that would eventually taper off as people would come to disregard W3C, but it would take time. It's in the browser vendors interest to keep W3C standards as meaningful as possible until W3C gives up entirely, but their involvement makes it less likely that it will be abandoned even if it is largely superfluous.