The way that I look at it is this.
Much of philosophy is about logic and analysis. Stoicism is about lived experience. When you're engaged in complex intellectual debate, there seems to me more to areas with logic and analysis. And that is what academic philosophy focuses on. But if you're trying to cope with life, Stoicism has a lot to say.
So Stoicism captures something important that a lot of people want out of philosophy. But it doesn't capture what's interesting to have complex discussions about. Let's take just one idea, https://mountainstoic.com/2015/06/03/on-the-stoic-acceptance.... How many conversations can you have about how it is better for you to go willingly along with fate than to be dragged kicking and screaming? OK, we can have another conversation about how the word "cynic" meant "dog" and so the Stoics were making fun of the Cynics in their dog and cart analogy. But really, there isn't that much to discuss. But there is certainly something to experience!
For a more extreme example, I believe that the most influential and widely read Greek moral philosopher was Aesop. But you'll almost never see his name in a book about philosophy. Why not? I think that it is because his fables, designed to speak directly to experience, offer nothing that looks like complex intellectual discussion!