That's a poor excuse given that a) mp4 support is pretty good these days and b) CSS already has responsive loading of assets. It's purely that to a man with a JS framework everything looks like a dynamic site. I highly recommend running Noscript to see how much of the Internet is broken because of this kind of nonsense.
Agreed. Web standards exist between the server and client. If you break the standard (eg. by disabling JS), then it's your responsibility when things stop working.
It's great that you have the freedom to do so, but you have no right to claim the website is "broken" as a result.
