That's explained carefully in the first 5 paragraphs, especially paras 1, 3, 4, and 5.
Note that I'm not claiming it can't do but I would be interested for the authors to point out what the actual benefits are.
All I see from their examples that clauses in Logica are much longer than SQL counterparts and that they are importing modules which (I assume) re-define already defined schemas which brings all kinds of different dependency problems that I'm not going to go in here..