When set to true, the browser will not abort the associated request if the page that initiated it is unloaded before the request is complete. This enables a fetch() request to send analytics at the end of a session even if the user navigates away from or closes the page.
https://developer.mozilla.org/en-US/docs/Web/API/RequestInit...
What do you think this means? It doesn't mean what you think it means.
Quoting LCOE and ignoring system costs disqualifies you for any discussion on this topic, sorry.