Webassembly runs in the browser, I click on the URL and application is in the browser,
And thats the problem. How do you check that the program you just ran (pretense) is free software? When you download something, you have not executed the program yet, and can make an informed decision if you wish to run it or not, e.g., if it is free software or not by looking at whatever tar-ball it came with, examining the license, etc. That is not normally the case with Javascript or Webassembly -- when you access the program, you're already executing it