"We haven’t engaged with other browser vendors regarding this change yet, but plan to submit a spec change proposal once the change is approved for Chrome."
So chrome just changes it. And then officially applys for the spec change, so other browsers might follow - or not.
I mean, why pretending at all, that you care about the spec, when you are fat monopolist?
This is how the spec process works:
1. You find out if you want to implement something
2. You find out if others want to implement something
3. You implement your something (for simple things in a testbed for complex things as an experimental change over multiple development versions)
4. You demonstrate the something works
5. You demonstrate others are intending to ship as well (For complex things you may have to wait until others are comfortable with their working implementations)
6. If you had a bad experience and many discussion points in 4/5 you go back to 4 and refine until you had a good experience and your spec is merged.
You imply the Chromium authors went 1, 3, ship because you read about step 1 happening. In reality they consulted with Firefox and Safari prior to merging code into the codebase or simply lobbing a spec proposal over the fence. https://github.com/whatwg/html/pull/6297
For me, that comes a bit out of the blue - and seems to be a "making facts" attitude by chrome, not discussing things.
Also canistilluse makes no claim about whether the deprecation matches standards or not. For reference the standards change was actually approved back in February, per the link in my above comment, so it is actually according to standards.