It's also an incredibly cynical ploy that'll probably damage belief in democracy more than anything. It's not a vote on whether Brexit happens because she called it after she'd already irrevocably started the countdown on that by triggering Article 50. It's not a vote on how Brexit happens because, as far as I can tell, she's consistently refused to be specific about that and no real negotiation with the EU has happened yet. (Edit: and the Tories have confirmed this is their election strategy: https://twitter.com/DMcCaffreySKY/status/854329597793632257) It lets May claim a democratic mandate for whatever she wants to do without giving voters any insight or say in what that is.