Apparently Edge had similar issues when a former dev spoke out against it. Now they're adopting Chromium with preview builds already available. Who knows?
I think Google are pretty slimey but it would be wrong to absolve Mozilla of any responsibility. They have crap like WebVR support and tacky cosmetic animations to make Firefox feel faster but it doesn't actually make it faster. It's good that they're trying to remove the XUL maintenance burden but at the same time there's more bloat coming in.
Mozilla should have got their act together years ago. They may be trying now but how long will it last before the last challenger falls to the Big G?@art