-- Last update, regarding deprecation, 31 March 2021
Hence 2021.
Same reasoning could be applied to Microsoft and Sony Playstation browsers, where neither of them support GL.
Fact is that after all these years, WebGPU still isn't here as stable version that one can rely on, and even then it is only a MVP with an incompatible shader language.
The code wasn't removed immediately when the decision was made so that people could continue prototyping compute shaders before WebGPU was available to test on. Game console browsers are completely irrelevant as their market share is so miniscule it's not even visible on most tracking sites.