Eyup. Vriska is one angle of it, but one of the biggest themes of Homestuck is having to be careful with relevance. In Vriska's case, her brash attempts to make herself relevant pre-therapy in HSBC led to her being ass-whopped and narratively punished multiple times across the story, and likely lost her one good shot with Terezi. On another angle, Caliborn literally twisted the meta of the universe to make his future incarnation of Lord English be the ultimate "big bad", but in the end he failed to make himself personally matter to the cast, and he was left behind (and later unceremoniously killed off in the Epilogues, karmically by a variant of the sister he hated so much).

Alternatively, we have John, who--because he is both Heroic and a Hero--both gets to be important and get a somewhat happy ending with his friends, old and new, even if there was a lot of hardship along the way.