I don't really see the advantage there over a service like Wealthfront or Betterfront, which offer automatic tax minimization, integrated handling of IRAs, and

I don't really see the advantage there over a service like Wealthfront or Betterfront, which offer automatic tax minimization, integrated handling of IRAs, and customizable stock-bond balances, or even just investing in Vanguard target date ETFs directly for similar returns with slightly lower fees.