Native apps, distributed in the browser.
Run "almost machine" code in the browser.
Lets browsers compete with app stores and installers.
Write C++, Rust... Compile it to WebAssembly... Run the code as a "web app".
You can play video games directly in the browser.
Ex. Open Photoshop in the browser, and send a link of the current project to someone to continue working. No sharing of files and installations.