That's an excellent response, but it leads to the question, why are we using HTML if X was successful? HTML over HTTP is now routinely used to deliver a GUI for

That's an excellent response, but it leads to the question, why are we using HTML if X was successful? HTML over HTTP is now routinely used to deliver a GUI for TCP, even though HTML was originally designed to deliver structured documents, and HTML comes with a great deal of baggage that muddies its ability to function as a GUI. It's become common to use a mountain of Javascript to try to overcome that baggage. Clearly, a fresh start is warranted.