I hate to be redundant, but the lack of threaded conversations here is really challenging. I would think that a comment parent ID would be trivial, but not having any idea what your architecture looks like, I'm sure it's probably more complicated than I think.
It's a design decision, not a technical limitation, but I hear you. Behind the scenes we do have all the data necessary to support a threaded view, and we've talked about offering both threaded and flat views as options. Just takes time. 🙂