Java apps didn't integrate with regular HTML. They were more like Flash apps with all those downsides. Even today JS is interpreted before compiling to bytecod

Java apps didn't integrate with regular HTML. They were more like Flash apps with all those downsides. Even today JS is interpreted before compiling to bytecode because the startup latency is much lower (JIT only kicks in once the background parsing is complete). Back in those days, the extent of JS was a few click handlers or similar. The JS interpreter would be done long before the JVM was even loaded into memory.