> post your applet on a web page, and anyone on the planet could run it instantly

"Instant" is a strange choice of words to describe JVM startup performance. I recall the UX of encountering an applet involving watching a Java splash screen while the browser is frozen.

The alternatives to Java were just as bad. Flash and friends were fast but couldn't do anything more complicated than animation for most of its life. In the Java heydays, you were doing either Java or custom ActiveX plugins, and both led to security popups galore and random browser freezes.

However, ActiveX usually required you to install components, while Java could just run first time.