Because that's just not how those weapons systems work, and not how guided ones do either.
I can accept that it's a game designed to be a game, but it makes simply no sense for them to scrape actual guided weapon systems to instead insert something such as this, it's just unnecessarily arcade.
It also seems to be a rather cheap feature really, looks like an engineer can singlehandely stop any armor he wishes, all while hidden behind a structure from across the map. Contrast this with the mortar strike for example which requires the user to maintain a steady line of sight with the target for a good seven or so seconds, and to plan accordingly for any target movement because of the shell travel delay. Not to mention the recharge time.
So yeah, out of good faith I won't do it. I think people get angry enough with me any my GOL anyway.
