Chromium is an Open Source project but it's important to note that it's also maintained primarily by Google. Blink, the web engine that Chromium is based on, is also maintained by Google.
Several years ago, Microsoft's Internet Explorer was the dominant web browser. Back then web developers focused on supporting Trident/Active X, Microsoft's non-standard, proprietary web technology, which created a limiting situation where having an online presence was dependent on what Microsoft dictated. Now the focus is on Blink. So yeah, tout Chromium because of its Open Source roots but it only exists within Google's corporate oversight. We had a period of several years of explosive Internet growth and it was diversity vs monoculture, but eventually diversity lost.
Right now Apple's WebKit and Mozilla's Gecko web engines are the last holdouts so there is that. Use a Chromium-based browser because you have a need to, but don't ignore the fact that once we intentionally create a situation that involves a single point of failure, that's not going to end well. We're all a lot more dependent on online services these days so back when some IE-based issue popped up, it wasn't a big deal.