No they didn't. First of all, you have no actual evidence that they are rapidly losing players right now. Secondly, even if they are losing players at the moment, the stellar weapon balancing patch is not the primary cause. People leave during content droughts. Bungie is going to be announcing Destiny 2 soon, so they are devoting most of their time to that. People aren't all leaving because the game is "shit", people are leaving because we've done everything in the game right now and in the meantime, there are new games to play.