Yes, but on a desktop, running a web app as a native application is tolerable, not great. On mobile, it's frequently a performance and battery problem and interacting with native APIs is hit or miss. This comment is similar to someone seeing the web stack used to build an application and saying "We already have something like this. It's called Win32 or Cocoa or GTK+ or Qt or writing directly to a frame buffer ..." Different technologies for customer demands, timelines, teams...

Modern browsers are heavy, each tab takes nearly 50MiB of memory where as native applications may take 2-10 MiB.

But it does work on all platforms.

One more issue is usability, since os desktop environments, doesn't support web-apps. One needs to pack it with electron or something similar to it.

Which increases your application size and memory usage.