I'm not sure either, but after reading the add-on description, it seems like it might be.
Unlike the "The Great Suspender" extension, this extension uses the native method for discarding tabs, which means that even if the extension is removed or the browser crashes, your browser will automatically restore everything for you.
It appears to me that the add-on simply allows for more control over which tabs are automatically or manually discarded, and it also indicates if a tab was discarded or not
Just because it's more modern doesn't mean it's a 1:1 replacement.
Wired is cheaper, and it has better quality, but it can also be annoying if you're doing sports.
It's the same for HD and SSD. I still prefer HD to store multimedia and backups, despite being slower and older than SSD.
There is no reason for them not to coexist.