the early papers in a subfield are often way clearer than the textbooks. the early papers need to convey understanding and interest un a new concept to a large skeptical community, whereas the textbooks just have to be "correct" and "thorough."
@ur_faec this is really cool to know but i'm so not surprised; i worked at a textbook publisher for two years and a lot of decisions on them get made for business reasons rather than educational ones, by people who dont know the subject, dont teach, or both...