A debrid service allows you to bypass the download limits of file-sharing websites (like 4shared, MEGA, etc.) without needing to have an premium account on each website.
They also provide functionally similar to seedboxes were they download torrents and then you download them directly from their servers. A lot of torrents are cached already (someone tried to download them already) and that's the functionality that's useful for Kodi or Stremio streaming as it allows you to stream media easily.
I have a perfectly good setup with torrent, vpn, sonarr, radarr, bazarr, it might be time to add streaming now.