Is there any advantage to sending data from UFs to an intermediate HF instead of directly to indexers?

Is there any advantage to sending data from UFs to an intermediate HF instead of directly to indexers? I recall reading that by relaying data UF > HF > indexer, there are certain advantages (e.g. running scripts on the HF ) before indexing, but in regards to DR will the HF store events for delayed transmission, if the indexers go down or the connection to the indexers goes down? I know there is a link on this topic but unfortunately I cannot find it. Thank you