Then you failed to utilize a better tactic, I don't understand how you can even have a tie, if your assault succeeds, then you can push the enemy over many planets before he entrenches another planet, if your assault fails, he will counter-attack you and fuck you up.
It is no different from other RTS games, technically you can have a tie of even forces in everything from command and conquer games to age of empires series.
I still don't see how this is a problem of a gameplay mechanic, and not a problem of you and your opponent using identical strategies.