I find WebKit to be a fine browser engine most of the time.

It is worth mentioning that the WebKit port for GTK does not support WebRTC and that it is not supported at all by Apple. It’s an effort by Igalia, one person from Red Hat and volunteers.

There’s also essentially no WebKit browser for windows. WebKit is often slow at adopting new web technologies as well.

All that to say - WebKit is not the example of a success outside of helping big corporations to make their own big proprietary browsers.