Meanwhile you can probably connect HTML client to already existing open-source non-HTML bot [1] using its bot-as-a-proxy feature. Adding automation stuff directly to HTML client shouldn't be hard, assuming network protocol handling and state keeping already provided for you.
So, nobody cares about more widely adopted <object/> which was supposed to be a solution for future media types and just happens to usually be more stable, have better perfomance and support much more media formats without having to invent new elements for each media type. Not even as a fallback.
[1] https://en.wikipedia.org/wiki/Openkore