Probably google. Chromium has made the decision to bundle all their dependencies instead of play nice with system libraries. Which means you either need to re-roll all of chromium when something is found, or you need to undo google's efforts. I don't blame distributions for refusing to give chromium poor support - it is intentionally not playing nice.
Yeah because when your software is at the scale of Chrome, "playing nice" with system libraries as you put it means your software is unreliable, difficult to debug and reason about. You want as few unbundled dependencies as possible.
That is their excuse, but I don't buy it. Plenty of other projects manage just fine.
All is far too strong to apply when there are as many different distributions as their are. Arch must have done the work to separate out all those dependencies, Debian has also stated their position is dependencies must be separated out as well.