An idle web app will use up just as much battery as an idle native app.
How about when they're not idle? There's probably an order of magnitude if not more instructions being executed in Electron, which eventually reaches the same OS APIs a native app would call directly. JITs still have overhead.
You're always going to end up with a larger code base and more complexity when making things cross-platform. Using something like electron is an excellent way to avoid all that complexity.
All you've done is moved the complexity to where you as a developer may not see it, but your users sure do.
How about when they're not idle? There's probably an order of magnitude if not more instructions being executed in Electron, which eventually reaches the same OS APIs a native app would call directly. JITs still have overhead.
You're always going to end up with a larger code base and more complexity when making things cross-platform. Using something like electron is an excellent way to avoid all that complexity.
All you've done is moved the complexity to where you as a developer may not see it, but your users sure do.