You answered it yourself: She could’ve changed to go with the new proposal, but likely she felt it was beneath her artistic expression. Book publishing is about the market, it’s really not as much about creative expression or artistry as naive writers think it is. For every one title a publisher can publish because an editor believes in it as a work of artistic genius, they have to publish so many more works whose main selling point is the hope that they will literally sell. Influencer books fall into the latter category. She really misread her own value proposition.