I agree.
While Blink doesn’t have the 95%+ market share IE enjoyed, Google has significant power. They recently scrapped W3C Pointer Events. There were various lame excuses such as “not being sure developers would use it”. Of course, not implementing it in Chrome means no one can use it even if all other browsers support it. (Note Pointer Events was initially devised by Microsoft. It’s a good idea, but silly politics have prevailed).
That said, what choice did Vivaldi have? Their own engine would have taken years. Presto is dead. Trident is closed source. Webkit was possible but is stagnating thanks to Apple. Gecko was an option but it’s not heavily used on mobile.