The difference is using one website vs many, proper controls of what each site can do, e2ee encrypted key sync btw devices, coming soon 2fa, etc. A product focused on managing your nsec the best way it can. 

 Thank you for the huge zap! 

 You store it in one page that doesn't interact much with anything – compared to storing your nsec on many pages that load content from all over the place and could have many many vulnverabilities.

Like using a password manager.