“Microsoft has already ditched their engine for Chromium; we’re all worried about Mozilla’s health and long-term (or even medium-term) viability, and Apple is only one competition judgement away from having to open up iOS to other engines.”
Some in the Chromium community argue for a web with one engine. Today a feature has to get through the W3C and convince rival browsers. With one codebase, whoever controls Chromium’s commit access defines the web. That is Google. Standards bodies are slow and messy, and that friction is the only check left.