You're reading a paper that analyzes the capabilities of a particular highly-constrained subclass of Turing machines. Actual research findings aren't necessarily going to be simple just because the model of computation being studied is simple. (Although a similar investigation into the capabilities of, e.g., a similarly constrained subset of Python, would probably tend to be a whole lot more lengthy and arduous.)

The parent's point is that the Turing machine model of computation admits a very concise definition -- roughly a page depending on brevity and formatting. An industrially viable programming language or hardware architecture typically requires a standard spanning hundreds of pages to define.