I'm not sure "helpful" is the right word. It may well be that Papadopoulus is the only guy who had any real contacts with Russia, and his were pretty pitiful, and nothing sticks to anyone higher than him. Or that may not be the case, and there's more dirt and he's agreed to reveal it in exchange for copping to a lesser plea. It is quite possible that Mueller's final revelations will not be criminal charges but nonetheless politically damaging and Republicans will have to go to the voters in 2018 defending their leader who (non-criminally) colluded with Russia to get elected. That's what the Trump apologists are really afraid of, and they're trying to get out ahead of it now with the narrative that if there's no criminal charges against Trump himself the whole thing was illegitimate ab initio.
Naturally, they are immune to the resounding irony of this line of thought as applied to 20 years of publicly-funded anti-Hilary witch hunts that never generated a single charge against her.