It shifts, rather than reduces, costs.
No altcoin has used a PoW where memory latency dominates computation.
Home users will never be able to mine profitably (except by claiming their electricity is "free"), but the hope is they can do so within an order of magnitude loss of efficiency.
Even altcoins that have tried this approach have seen custom hardware appearing if the coin grows popular enough.
The approach just seems to be a desperate hope that home users will be able to mine profitably, but ultimately it still fails because those with more resources will win out.