There are usages outside of the browser too. We are using wasm as a runtime for applications and modules deployed in small IoT device. Wasm helps overcome the typical limitations of those devices giving platform independence, sandboxed environments, ability to verify and sign modules ahead of deployment, allows developers to program in dominant languages and compile to wasm, and still retain a low footprint which is critical in this context.
There is a more detailed overview here: https://www.midokura.com/why-webassembly-is-perfect-for-tiny...