Google had very purposely raised the bar by putting like 5x-8x more competent engineers than the Opera core (non-platform/UI-specific stuff) team had, working on inventing and implementing random new web standards that they then promptly started using on google.com properties. Think e.g. 500-800 engineers compared to 100. We simply couldn't do the same. Then this ratio started growing until it was obvious that it would eventually become an existential threat.
They used their financial success in one business area (search ads) to become dominant in another area (browsers) in a clever and perhaps not entirely legal way.
Now Chrome works well enough as a browser and has so much market share that it exerts too much control over its users and the Web, and it's unlikely that anything will be capable of obsoleting it in the near future.
Or just fork webkit/blink and aggressively refactor.
It certainly feels like Google is using the same playbook for web standards. They've created enough churn that no one else can ever hope to catch up in implementing those standards.
When Google products stop working on some competitors browser they can simply say "it's just web standards" and feign ignorance.
I really liked old Opera and even Edge for their engines that made the web pages feel snappy and somewhat different than the WebKit monoculture.
I was a huge fan and tried to convert my friends from 2004-2012. It was tough watching them slowly convert to firefox or stay on IE.
It really didn't help that Opera handled transparency so poorly. That made myspace pretty much unusable.