Hatsune Miku / Vocaloid - Hatsune Miku: The Later Years - Art by VERTIGRIS

Ditto, If anything I feel that vtubers help the vocaloid scene what with many of them doing covers of vocaloid songs and get them trending.

Crypton has always taken a very hands off approach to Miku and allowed the fans to create pretty much whatever they want with her. It's the fans who write and compose the songs and steer the general direction of the movement. Even the whole Leek thing was something that was randomly associated to her by a fan and it stuck ever since. This goes hand in hand with her blank-slate persona as to not inhibit any creativity or artistic expression.

A completely crowd-sourced/grassroot music scene with singing computers was born, Miku being the defacto figurehead of the whole thing.