This request has already been made several times, with no response. I recently found an old topic that has an interesting comment on it, so I'm reopening the application.
The reason is that pauseOnBlur makes it impossible to create any real time multiplayer P2P game in Construct.
To understand why, just open the engine's own multiplayer examples and press alt+tab as the host. The second player will lose movement. Even if the objects are not synchronized, the player stops running events that would be important in a Real Time game.
Is it possible to somehow prevent the game from pausing when it's out of focus?