Considering that people mostly use either webapps in a browser, or Electron-based 'native' apps, does saving 300 MB with a specific app really makes that much of difference?

I do understand that macOS APIs and libraries are easy to use, development experience is (at least in my opinion) better than with Electron + framework of your choice, and you can achieve better integration with the OS, but I don't think that saving 200-300 MB is really important to the end users.