The problem with these Chromium based browsers is that this is helping strangle the only real alternative to Chrome. You might not sell your soul to Google, but you still help Google keep their stranglehold on web standards, etc. Of course, a single person is always irrelevant in the big picture, but combined Vivaldi, Brave, etc. are helping strangle Firefox and helping prop up Google's heavy hand on web standards.
It's Firefoxs fault that Chromium took over, Firefox just had to copy what Google did with Chrome (which is make a version that is easily integrated in other applications). It had years to do so, and did not. I am not blaming Firefox for the rise in Chrome, but I am blaming them for the rise in Chromium. They have a solid alternative and didn't care enough to capitalize on it. Who knows in another timeline with changes it's possible Firefox Gecko rained supreme in the embeddable space.
So let's say you're a bunch of ex-Opera employees who want to start a new browser, are you going to write an entire browser engine yourself? No who has time and money to pay hundreds of developers for years just to catch up. You're going to use a off the shelf version and modify it.
Can you use Firefox? No, good luck integrating it into anything, it's extremely difficult. Firefox actively suggests not trying to embed it.
Can you use Chrome/Chromium? Yes it's easy and readily available SDK that even has thousands of implementation examples.
Can you use Webkit? Yes you can, but it's only managed by Apple and a select group of smaller companies, you are at the mercy of Apple. It also has poor support in some areas.
So you end up going through pros and cons and Chromium is the result. It's not the result of a bunch of Google loving companies, it's just pure developer economics. It gives you the best possible start.
Embedding the browser is a very small issue compared to what Google actually did: spend money, put chrome ads everywhere on the internet, spend more money, push chrome in its results and pages, spend more money, put chrome ads in physical space. The features don't matter that much - there were a couple of years where you were simply bombarded with ads about a better browser. It worked and they made normies care.
You forgot one: IIRC, Chrome came bundled with some popular Windows applications.
> there were a couple of years where you were simply bombarded with ads about a better browser
Let's not forget the whole context: Chrome's main opponent back then was not Firefox, but Internet Explorer. And it did help reduce Internet Explorer's usage share, so much that it was abandoned (again) by its developers.
Ironically, it was copying google's chrome LAF that led to the decline in firefox since v57.
They had to kill XUL to be able to keep up with the Chrome UI changes, and at that point killed off a vast amount of plugins, leaving firefox with no real advantage over chrome, but all the speed disadvantages compared to chrome.
I think a big reason developers don't choose WebKit is due to the Windows port requiring significant work, and most new browsers want to support Windows.
On this thread there was a rough estimate of $1M - $2M USD to do that work. It's probably not far off the mark.