They got rid of Littlefinger in a more assassination-style manner, which meant the siblings foregoing much of a trial for him.
One question going into Season 8 is whether the Starks will face any heat for taking out Littlefinger.
They got rid of Ramsay Bolton in a battle.
With Jon Snow bending a knee to Daenerys in Season 7 and his siblings executing one of their enemies while he was away, the Starks could be in for a bit of controversy when Season 8 rolls around.