For example the current controversial change: Google says "slow web is bad" and deprecates an API that allowed extensions to do almost unlimited work for any web page. Oops. Adblockers depended on that and did want to do almost unlimited work for any web page, and that wasn't a bug, but the API gets dropped, AIUI because Google wants performance. The reason doesn't matter though. Google gets to set the agenda, no matter what its reasons are.