It shifts the incentive for people with swarms of small accounts to delegate to either one voting account or a paid delegation service rather than have each account vote with a bot. That may not affect content spam but it does reduce vote spam (in the case of delegating to a paid service, it _may_ even reduce content spam, with many variables). Although for people with small accounts receiving delegation, they won't be able to do that (since redelegation isn't possible), so the problem persists. At least in that case a possible solution is getting the delegation removed.