As a tangible example, in response to this one Chrome engineer Tweeted "breaking changes happen often on the web, and as a developer it's good practice to test against early release channels of major browsers to learn about any compatibility issues upfront."
That strikes me as the wrong attitude when you're working on the web. Change should be a last resort, not an expected side effect of you achieving some other goal.
Also since web browsers are taking more and more of the operating systems responsabilities (providing API to buid applications) they should be more careful with compatibility of applications. Reversing the responsability is not acceptable.
Coincidentally I just got burned today by some of those Chrome changes: a web app I'm developping has its container exposed on port 10080 for some reason. Impossible to open it with Chrome, because it decided most ports are now "dangerous". Took me 10 minutes to figure out, as it was working fine before. As relaunching the thing involve some manual steps, I solve the problem using Safari... It is becoming more and more difficult to do things not vetted by Google, and that's scary.
That strikes me as the wrong attitude when you're working on the web. Change should be a last resort, not an expected side effect of you achieving some other goal.