Reading the article, I felt like I was back in 1996 reading about the Java bytecode compiler and the JVM plugin for the browser. Java had such great promise for web page-hosted code, that would be portable, performant, and safe. Why would one think WebAssembly will succeed where Java failed? (Well, Java did not exactly fail, but its purpose and typical usage radically changed over the years.)
Java failed because - it depended on an installation outside the browser, poorly versioned - and a plugin too, which was extra noise for the user, and not nearly so pain-free as Flash's was - it was not , under any circumstances, performant (this was before HotSpot) - AWT was truly, thoroughly, god awful (this was before Swing) Finally, it was caught between two realms. Clunkier than JS and more difficult to work wit…
It was performant enough for one of the most popular games of all time, Minecraft, which was originally a game in a Java applet.