I don't really understand the appeal of this;

For fans this creates unexpected bills and forces them to be prepared for the creator to post at any second if billed automatically. With Patreon or Fanbox you know what you will pay every month and don't get hit by a surprise

For creators it removes the monthly income they could expect and prepare for, instead now it may push for them to make low quality posts just to get income every month. I would personally prefer a good post whenever it is ready compared to a forced one every month.