Prowlarr works a bit differently, it auto configures each indexer on sonarr and radarr and will automatically remove them if they go down and things like that.
With jackett, you're not really supposed to use the "all" endpoint and if you want to do it properly you still need to configure each indexer on radarr and sonarr.
The net result is its much faster and more efficient, especially when you add more than a couple of indexers.