I believe rerere is a local cache, so you'd still have to resolve the conflicts again on another machine. The recursive merge doesn't have this issue — the conflict resolution inside the merge commits is effectively remembered (although due to how Git operates it actually never even considers it a conflict to be remembered — just a snapshot of the closest state to the merged branches)

The recursive merge is about merging branches that already have merges in them, while rerere is about repeating the same merge several times.