But for 99.9% of people it frankly achieves roughly the same goal of being able to hide from cookies with minimal effort.
The goal isn't to hide from cookies, it's not having to click through cookie consent modals. Having ephemeral sessions actually makes this problem worse because sites actually use a cookie to track whether you've consented to the other cookies the site wants to use. So not having the "has/has not consented" cookie causes the modal to appear, making you set your preferences every time you visit the site instead of just the first time.
The problem isnt the cookies. The problem is the consent popups.