The rise of javascript and its server side runtime is due to the immense pressure that language had to evolve to make the web what it is today.
Web-assembly is the next step and evolution of this runtime. I can only imagine the sheer number of man hours poured in to javascript to offer the functionality it has today while balancing with security and sandboxing. Nodejs is a different story; Take a look at Deno and its origin.
Web-assembly is sandbox-able run anywhere, ubiquitous runtime which isn't owned specifically by a corporate overlord, and is also which has/or is set to have the evolutionary pressure javascript has. This is huge! Way to go Wasmer :)