Dispensationalism has absolutely nothing... to do with a literal approach to Scripture. That a wild boast just with icing on top of it to try and make it look attractive. A dispensation of time in God's Word does not help interpret God's Word chapter by chapter, line upon line. The Holy Spirit does.
Part of John Darby's Dispensationalist theory DOES include the Pre-trib Rapture theory. With his idea of the Church being raptured prior to the tribulation with Israel left behind is a theory Darby linked with his Dispensationalist theory. Darby's ideas of national Israel existing as a kingdom on earth during Christ's 1,000 years reign with Christ and His Church dwelling in Heaven is another one of Darby's theories attached to his Dispensationalist theory.
Darby keeps Israel and Christ's Church separate, when The Bible has no such doctrine for the end. Darby's secret rapture theory is not Biblical either. Jesus declared His 2nd coming to be after... the tribulation, per Matt.24 and Mark 13. In 2 Thess. 2, Apostle Paul showed the Antichrist must come first prior to Christ's 2nd coming to gather His Church.
E.W. Bullinger, an 1880's British Christian scholar, believed on Darby's 1830's secret rapture theory, and he took Darby's Dispensationalist theories farther and started what is called Hyper-Dispensationalism, a movement that teaches the only Bible Scripture applicable to Christ's Church are the Pauline Epistles.
So there's no sense in trying to white-wash an old un-Biblical doctrinal theory from John Darby, just because it's been around 180 years since it was started and new babes in Christ today are not familiar with it.