WebAssembly somehow does not seem to be able to break-through, unlike HTML, CSS, JavaScript did.
It is more of a silent thing. Running in the background, internal libs, deployment tools, plugin tools.
But also - it's lacking things like a unified positioning + required knowledge to understand it is quite large compared to average dev + most people have no real use for it. It's mostly too "abstract high level" and "low level" for most devs.
Or the people who write wasm don't talk too much about it. My OSS work (https://github.com/mickael-kerjean/filestash) has tons of it:
1. to create web versions of applications that are traditionally desktop only to render things like Parquet, PSD, TIFF, SQLite, EPS, ZIP, TGZ, and many more, where C libraries are often the reference implementations. There are almost a hundred supported file formats, most of which are supported through WASM
2. to create plugins that extend the backend and add your own endpoint or middleware as a way to enforce the code run in a constrained environment without the ability to send people's file out
3. in the workflow engine to enable people to run their own sandboxed scripts without giving those a blank check to go crazy