wait what did equius do for the plot. hes my baby and i need to know

He built Aradiabot which allowed the trolls session to progress the way it did and actually come to fruition. He built Vriska an Arm. He gave Tavros legs.  Plus he had some great personality growth which we didn’t really get to see a lot of. And not to forget one of the best logs in the comic when he raps  recites some Alternian Slam Poetry with Dave.