> More generally, I think WASM is starting to challenge the whole "there can only be DOM/CSS/JS" thing that has held web developers back for two decades.

No one was held back, people keep choosing the web because it's consistently better.

What I think is crazy is this drive to take something that is working great (the Web), and then jam in an approach that has already failed multiple times. We already tried several iterations of binary-heavy, non-transparent, non-searchable, non-web-native, second-ecosystem application platforms including Java Applets, Flash, Silverlight, etc. They had a chance and users rejected them.

If you think the web sucks, then by all means, I encourage you to make a compelling alternative. If it really is better then people will use it. But maybe don't try to spoil the working recipe of HTML/CSS/JS, especially if you don't fully understand the reasons why it keeps winning.