D&D 5E Creative solutions to the hypothetical GWF/Sharpshooter issue

[Leatherhead]

Well, stunting is called out as something that can arrange for it from generous GMs - ingenious players can get advantage for doing cool things with that Cunning Action from standard rules. A melee halfling rogue can use hiding by constantly weaving between can be used between people. Even in combat, people don't have 360 degree vision, so they do have blind sides. A thief can Use An Object, so throwing sand in someone's eyes, or similar, to temporarily blind them would generate Advantage. Arcane Trickster uses the Mage Hand with his Cunning Action to get Advantage.

I could go on; there's plenty of ways. Flanking's just not one of those ways by default. Admittedly, there will be some times it won't work out, and then you can TWF as a backup plan while someone is within 5'.

Oh, in my experience, melee rogues are never by themselves in combat, at least not for any extended period of time. Which makes using a bonus action to throw pocket sand, just to gain advantage on a single attack highly inefficient. Even without flanking, two attacks are better than making one attack with advantage, due to the potential for extra damage, even if it is just 1d6+Dex.

 

[Mephista]

Oh, in my experience, melee rogues are never by themselves in combat, at least not for any extended period of time. Which makes using a bonus action to throw pocket sand, just to gain advantage on a single attack highly inefficient. Even without flanking, two attacks are better than making one attack with advantage, due to the potential for extra damage, even if it is just 1d6+Dex.

Actually, its really not on both counts.

No, the melee rogue is not by himself or herself in combat. That doesn't necessitate that you're going to have other PCs granting advantage. Sure, if that happens, its better to make two attacks (again, unless you need to disengage to cross the battlefield, or dodge, or something). But the rogue, in a party that's not built that way, actually is better off with generating their own advantage.

The average dpr output on a single attack with advantage is actually higher than making two attacks without it. Remember, that second attack on a rogue is 1d6 at the most (could be less), not 1d6 + DEX. You lose out on that extra DEX damage if your second d20 hits and your first one doesn't. Start adding on how the whole Attunement system works, and you're likely to have one really good attunement weapon, and your off hand be a crappier weapon, meaning you deal more damage when that first one hits.

It might seem like using two weapons is better, but it actually isn't.