Yup. Basically at this point it's a matter of false expectations.
In fact, I could argue that I've expected the exact thing to happen with the following support:
1. The S.D.M.G., before 1.3, was considered to drop from the final boss. During that time, the S.D.M.G. did not have any flashy effect. As such, expectations should have been the same [however, people would have expected its stats to improve due to being overpowered by the moon events and fishron's drops. This is valid as the argument is objective: The moon drops were better than the gun.]
2. The S.D.M.G. is considered to be part of the pattern of accurate machineguns: Minishark and Megashark
2-1. The S.D.M.G., along with the Minishark and Megashark, do not have any flashy special effects, and as such should be expected to work the same way to keep the pattern.
3. The S.D.M.G. works like an endgame weapon would - it's heavily effective when used on the rest of the game.
4. The S.D.M.G. works much like a majority of the ranged weapons - its mechanics are to straight up aim, shoot, and kill. Variations to ranged weapons are determined by the weapon type [bow, pistol, xbow, shotgun, machinegun, rocket] and bullet type [ichor, crystal, luminite, etc], while a few others were completely unique [Stynger, Nail Gun, etc]