Yeah, but the to hit is for a ship moving in a straight line at a known speed while the beam is on the way. You'd give it a lot more time to react, which should lower to hit chances.
There's no reason lasers and other beam weapons couldn't just shoot further, and just track the target like Mass Driver packets do to planets. The 5 second tick time combined with light speed is a completely arbitrary way to handle things either way. Yeah, it's "unrealistic", but so is the current situation. Light can travel a far greater distance than 5 light seconds.
The more important issue than realism is, does this make beam weapons effectively worthless? Seeing how most people play this game, I'd say yes. Beams seem to be mostly for defense against the other guy's missiles. Why choose the super duper short range weapon systems over the super duper long range weapon systems?
The fact is, the game already has FTL sensors. Active sensors can see any distance in an instant. That means whatever they are actively transmitting travels faster than light. Why can't that be weaponized? Why are we pretending light speed is a limit when it obviously isn't here?
So I think the whole 5 light second limit should be removed, and let the tech just keep scaling up the range as you go, with some scifi sounding names for the tech that imply FTL. Remember, this game world already has an entire extra fluidic dimension under the surface that throws the laws of physics out the window anyway.
I suspect steve enjoys playing with missiles more than beams (Probably a lot of aurora players do, after all, there's more designing with the missiles) and so he doesn't mind beams being subpar.