Sure, i know that there are standards
But Webkit Engine/Blink Engine do have the trend to be a "bit more flexible" in standards 
There is for sure a reasons why more and more sites are "optimized for Google Chrome only/watchable with Google Chrome only".
Even if Browsers do have these standards, Marketshare is influencing the acceptance or non acceptance of some browsers. Opera had seen in the end only the chance to use Chromium to keep up with the new trend to get things done in the web.
Mozilla speaks these days very loud and noisy about their new engine "Servo" - but i would not be too surprised to read one day that they dropped the plans because it costs too much money and switch to Webkit/Blink too. At least it would be a move which would be "exactly fitting of these Day's Mozilla Organization"
And btw. If they plan to remove most customizations, i personally would prefer a Webkit Firefox with almost none customizations as compared to a Gecko Firefox with almost none customizations.
Webkit is just simply faster and as already written.. more flexible

There is for sure a reasons why more and more sites are "optimized for Google Chrome only/watchable with Google Chrome only".
Even if Browsers do have these standards, Marketshare is influencing the acceptance or non acceptance of some browsers. Opera had seen in the end only the chance to use Chromium to keep up with the new trend to get things done in the web.
Mozilla speaks these days very loud and noisy about their new engine "Servo" - but i would not be too surprised to read one day that they dropped the plans because it costs too much money and switch to Webkit/Blink too. At least it would be a move which would be "exactly fitting of these Day's Mozilla Organization"

And btw. If they plan to remove most customizations, i personally would prefer a Webkit Firefox with almost none customizations as compared to a Gecko Firefox with almost none customizations.
Webkit is just simply faster and as already written.. more flexible
My Computer
At a glance
Windows 7 Ultimate x64AMD BullldozerCorsair VengeanceGeforce GTX 280
- OS
- Windows 7 Ultimate x64
- CPU
- AMD Bullldozer
- Motherboard
- Sabertooth 990FX
- Memory
- Corsair Vengeance
- Graphics Card(s)
- Geforce GTX 280
- Sound Card
- Onboard Realtek Sound
- Monitor(s) Displays
- Samsung Syncmaster
- Hard Drives
- WD ones

