Developers will do whatever browser vendors push them to do, and they clearly decided they did want to push HTML5 agenda instead.
Now, Firefox is for all purposes dead, just fairing a bit better than The Year of Linux Desktop, Safari with Apple doing its own thing thanks iDevices market share, and everyone else is basically a reskinned Chrome, or Electron garbage, solidifying ChromeOS as the future we all deserve to have, as the IE lesson is long forgotten.
Now, Firefox is for all purposes dead, just fairing a bit better than The Year of Linux Desktop, Safari with Apple doing its own thing thanks iDevices market share, and everyone else is basically a reskinned Chrome, or Electron garbage, solidifying ChromeOS as the future we all deserve to have, as the IE lesson is long forgotten.