"No, they don't like doing things that way, from what I gather. Memory gaps show up, and people get suspicious. They let us keep our knowledge about Horcruxes when Dumbledore told us... meaning that they might be willing to sway things certain ways, or try to keep some sort of balance. I can't figure out why they didn't stop Tom when he was getting the information from Slughorn, unless back then they never expected the rise of Lord Voldemort."