I think that's a bit of an exaggeration/retconning. Between NetCaptor, Maxthon, etc., that's the era that gave us huge innovations: tabbed browsing, popup blockers, ad blocking, site groups, search in the URL bar, and so much more. And CSS, and GeoCities, and streaming video and animated applets/games/Flash...
There was so much innovation going on, the real difficulty was in being able to display your content to your audiences. CanIUse wasn't around then and there were huge incompatibilities between IE, Netscape, Opera, eventually Phoenix, etc.
It wasn't the diversity in engines that allowed innovation, it was the market exploring different features and eventually converging on the ones that people really wanted. If anything, having redundant engines slowed down actual development. IE6 was king for a few short years, and in those few years the web was more stable than it ever was before or since, and content was king instead of engine differences.
For now Chrome has the best of both worlds: market dominance and rapid innovation. They have no meaningful challengers anymore... Firefox/Gecko is dead and WebKit is only a thing because of iOS, and thankfully it at least shares a heritage with Blink.
I think your link proves the opposite point: that the web ecosystem is wasting time on interop instead of actual features. We don't need three renderers that do roughly the same thing, but nothing exactly the same. It was Chrome's hegemony over the last 5-10 years that actually gave us huge leaps in web usability, dev specialization, best practices, and content creation. The real changemaker was making Javascript safe and fast enough that native in-browser programming became a reality.
There is no such thing as web standards in reality, only Blink and WebKit's mostly-compatible implementations. If we could move past that delusion and just converge resources on Blink/V8 and just evolve that, the web would be better off for it.
Thanks to Mozilla we then got asm.js, wich evolved into Wasm and ultimately replaced NaCl.
Now imagine there was one engine and Google could implement whatever they wanted? RIP privacy and well-designed standards.
Mozilla is largely Google funded anyhow. If they wanted to drop funding and go their own way they could do so anytime.
It would have a far better chance of working if the Chrome/Blink team were spun out of Google into a nonprofit that is protected from the financial influence of Google.
Then Flutter came out of nowhere and reintroduced everyone to Dart again.
Chrome has been doing some terribly shady stuff with Blink whether we look at their various tracking proposals, “portals” which are a blatant attempt at ossifying Google as basically the internet itself, or the extreme standard-stuffing they continue to participate in to ensure no further competitors can pop up.
But beyond that nearly every point you raise here is completely off.
WebKit is superior to Blink, in almost all ways. It’s simply a much better browser and has been for a couple years now. Faster, lighter, and supports nearly everything you need. Every time I’m forced use Chrome, it’s like having to walk through a shady neighborhood - I literally can’t wait to close it. That thing sucks memory and battery in a way no app should, and Googles numerous shady tactics in trying to get you to login so they can avoid your privacy settings is downright hostile.
Leaps in best practices? Is that a joke? Web Components pushed by them is one of the worst things to happen to the web. Half of the standards they’ve pushed are actually regressions.
And again, Chrome is much slower and more bloated. If anything Safari is far better today for delivering a more native experience.
And your last paragraph is very much the kicker. The funny thing is the Safari thing is the only thing keeping Chrome in check. If this is what they’ve tried to get away with with Safari, I don’t understand how you can be advocating for even less competition. Interop is an incredible project that will save developers massive amounts of time, while ensuring we don’t end up with the most privacy invasive and manipulative company of all time controlling the web for the next 1000 years. Thank god for Safari.