As far as why we use the web for "apps" (which seems to mean any site with any non-trivial interactivity provided by javascript, as opposed to any site emulating the function of a native application, which there are few of,) we do so simply for the reason that the web as a platform already exists, and is ubiquitous, and provides a single development distribution model for text and interactivity, and that is more convenient than forcing text to be in one place and everything else to run in separate application spaces.

Running code on the web was conceived of as a possibility from the beginning, the premise that it was only ever supposed to support static documents, but then got 'corrupted' into supporting "applications," is kind of a modern retrofiction.

Also, the premise that only static documents contain information, whereas applications don't, isn't correct. The vast majority of what are considered "web apps" are, functionally, just dynamic multimedia documents.

For everything else - actual web applications - WASM will probably be the solution.