Well, Microsoft has a huge responsability when it comes to the failure of ES4. No matter what you say. Especially since now everybody is talking about adding type declaration to javascript. We add these in ES4, MS clearly didn't want it because it would have made JS too powerful and threaten MS business.
Yes we were either all there, and the new generation of devs have heard the stories. It doesn't matter anymore and it's exhausting to here people harp on decisions made 15 years ago by a bunch of old dudes who are retired now.
15 years ago? the ES4 stuff happened in 2009-2010. that was 5 years ago.
As for whether the failure of ES4 was Microsoft's fault, no it wasn't. It was ES4's fault. Microsoft and Douglas Crockford merely pointed out the irreconcilable mistakes in design in ES4. The last thing Javascript needed was more bungled up mistakes and weird things in it. In particular, the issues with ES4 were around the packaging system and how it combined with namespaces. Upon close examination the design, lifted straight out of actionscript, just wasn't going to work on an ASYNCHRONOUS web.
Works fine in a binary blob of flash all downloaded in one go. But when you have to download individual files separately all hell would break loose.
ES4 wasn't all or nothing.What does the type system or the class system has to do with asynchronicity? nothing.And by the way,one can totally LOAD classes and packages asynchronously in AS3. So that's not a valid argument. Crockford didn't like ES4 because it's Crockford like he doesn't like a lot of ES6 features, like he doesn't like the NEW operator. As for Microsoft they were just not interested in working on IE anymore, they didn't give a damn and just wanted to push Silverlight everywhere.
That's the story here. So your account of the events is a bit misleading.