SusshiRoll And why would Webnovel use Patreon for this? Also, donations and the like is just too unreliable as an income for anyone. Patreon earnings can be so high precisely because of advanced chapters (or paywalls). Furthermore there's now gifting which goes to all three parties again, so there's no reason to add Patreon into the mix.
They are the ones hosting the work, creating the business model, strategizing with partners, hiring translators (taking the risk of losing money translating all these works), contracting with the authors, grooming the authors, managing their content to better the interests of the authors, etc. All of these are reasons for Webnovel to get a cut too.
Authors, Translators, and Webnovel share the Spirit Stones equally percentage-wise.