Can you provide some reasoning for why this is necessarily the case?

Arrogant people preemptively declaring failure and trying to enforce their baseless declarations on others is what brings innovation to a crawl.

Come on now, that's a bit harsh. There are really smart people who have been trying this exact thing for years without success. Microsoft tried harder than anyone to make "JScript" part of .NET but finally gave up and Windows 8 has 2 first-class VMs.

It wasn't in the browser though. So it's a different story.

Without success because people like you have been fighting them every step of the way trying to hold back progress. It's hard to overcome inertia, and it's almost impossible when there is an organized resistance. It becomes absolutely insanity-inducing when said resistance uses its own success in warding off progress as ammunition for holding back progress.

I'd say I was exceedingly un-harsh, even downright polite, considering the long-term damage that has been inflicted.

That's just shooting the messenger. The comment about 'enforcing ... on others' is completely unwarranted.