It is actually harder. The anime aesthetic was literally designed to facilitate easier 2D animation. Notwithstanding the aesthetic itself being very popular (and thus more familiar to designers), many "non-anime" v-tubers like Layna Lazar or Juniper Actias will tend to incorporate anime elements because it's what they know and it's easier to implement, even if they're not trying to follow the "virtual idol" model set by Hololive and the like.

Also, one has to consider that this is an entertainment market almost exclusively bound to Twitch and Youtube, and it's counterproductive having an avatar that isn't going to appeal visually to the masses, generate clips and be supported by the algorithm.