Problem with Advantage+ Shopping Campaigns

There's a potential problem with Advantage+ Shopping Campaigns. Advertisers have virtually no impact on targeting, which isn't necessarily a problem in itself. But, you can't exclude people who bought the product that you're promoting. While that may be fine when a product can be bought multiple times, you'd probably want to exclude people who bought a product that can only be purchased once. And the Existing Customer Budget Cap isn't a solution.