As an avid Linux user, I can't help but agree with the core of your argument. Open is always better, especially for posterity. But the aspect of Flash that has

As an avid Linux user, I can't help but agree with the core of your argument. Open is always better, especially for posterity. But the aspect of Flash that hasn't been fully replicated by HTML5/JS/whatever is the fully integrated workflow. That took away much of the underlying woes with environments and configurations. All you did was install Flash, make your game or animation, and a SWF was produced. This ease of beginning surely was a springboard for so many creators and animators, like the Newgrounds community. I'm also partial to the idea of not everything being done by the browser, and instead plugins specialising in their respective area. The effect of moving everything into the browser only contributes to the Google-led near monopolisation of rendering engines.