From my ultra naive perspective - this was always the case with me. At the very beginning, Virtual DOM manipulation/management was beyond me. Then they updated

From my ultra naive perspective - this was always the case with me. At the very beginning, Virtual DOM manipulation/management was beyond me. Then they updated the engine to React Fiber. If I thought I understood anything under the hood, I really didn't then. I believe the author is talking about tiny unexpected side effects as a result of the complexity. Like on a particular hook, 1+1=2 out to 7, 9's. But if you do it just in the right way, you'll get a weird side effect (i.e. 1.0+1=3). This is a typical result of being a ultra power user and I feel the author's pain. FWIW, I don't think being a black box is bad. Kernels are black boxes, CPUs are black boxes, to so many of us anyway. The spirit of what the author is trying to make is - this black box isn't completely predictable. It's only mostly predictable - it needs to get better so everyone can rely on it.