As there are increasingly fewer non-Chromium based Web browsers, it becomes increasingly likely that Web sites & apps overfit to Chromium. At that point, you no

As there are increasingly fewer non-Chromium based Web browsers, it becomes increasingly likely that Web sites & apps overfit to Chromium. At that point, you no longer have Web technologies. You have Chromium technologies that happen to be served over HTTP. Since these apps & sites will invariably not work with Firefox, users leave Firefox for a Chromium-based browser, making things even harder for Mozilla. So, the issue isn't just that MS adopted a Google open source project, but that in the process they've abandoned an alternative rendering engine. Web developers perpetrated this cycle once before with IE6. It's easy to look back at how bad IE6 was because MS became complacent. In its day, however, IE6 was easily the best browser out there. And MS decided waiting on a standards body hindered the speed of progress, so they forged ahead with their own features and hoped the standards bodies would later incorporate them. If not... oh well. And since 90+% of the Web used IE6, developers developed their sites for IE6, rarely ever testing in anything else. It's likely Chromium won't stagnate the same way that IE6 did. But in a way, that makes it even harder for Firefox to regain market share. As a Firefox user, it's a bit embarrassing how many sites & apps I encounter that are Chrome-only. Or, if I report an issue to a developer they tell me to just switch browsers.