But here's the way I look at it: OpenGL was created to abstract over graphics hardware and operating systems both at once, and yet was intended to be high-level enough that it could be called out to directly by application developers (including game developers).
It was what people needed at the time, but I think it was trying to do too many things in a single layer of abstraction, and these days it isn't doing a great job at any of them. It's known for being slow. Most people don't write it directly anymore; they use a game engine or library and only write shaders directly. It performs inconsistently between OSes.
Whereas Vulcan, and even more so Metal, are decidedly lower-level. They abstract over the hardware and that's about it. This enables the higher-level libraries and engines that people were already using to be more fine-tuned and performant while still allowing graphics hardware to remain a commodity.
In this context WebGL is interesting because it's also an abstraction over Vulcan/Metal/DirectX, while remaining lower-level than most of those other libraries and engines. It's really very much like we've split the OpenGL layer in two and ended up with one layer focused on performance within a given OS, and another layer focused on providing a modern, ergonomic API across all systems.
All in all, I think this is a pretty good way for things to have progressed.