I think you are mixed up in your approach to history in who the rationalists and liberals were. The dispensationalism of Darby fell on the heels of German rationalism. Progressive dispensationalism fell on the heels of the dispensationalism of Darby. Now the dispensationalists of today are evaluating the finer points of progressive dispensationalism."Hath God said" originates with Satan. Higher Criticism has its origin among the German rationalists who rejected the miraculous as their very basis for intellectual pursuit of the Scriptures.
While I am unable to agree with the liberals, it was they who brought to us the way conservatives interpret wisdom literature.