Flash games had some soul at least. Im not sure what if was, but after flash died and we got all these fancy web graphics technologies web games felt technically impressive, but sterile and empty.
Here for example for Chrome, chrome://gpu, see the amount of disabled features across your devices.
This information isn't available to games, like in native code, thus it is not possible to work around issues preventing the rendering to work as expected.
Additionally there is no quality debugger available, only a few toy extensions when compared to Flash Stage3D tooling, or what is available for native apis.