Thing is as long as web engines evolve you can't have this. There was a moment say 3 or 4 years ago when some people, including key jQuery devs, were saying that Firefox should just switch to WebKit and that would solve web development because there'd be only one engine to target.
What actually happened is that Android phones got stuck on several outdated WebKit versions, Safari on another, and then Chrome forked WebKit into Blink.
So instead of one engine, you now have...like 5 or 6, realistically.
Trying to target standards compliance instead of relying on browser quirks is still the best strategy, both for devs and the ecosystem. It was in 2002 and it still is in 2017. Without it, we wouldn't have iPhones, Android phones or Chrome, for crying out loud.