Maybe we older people, who had initially only mass spectrometers available, see the use of seperation/purification steps ahead of MS differently. One doesn´t even need a complex matrix for MS to fail. As an example from a very long time ago: I had a highly pure mixture of geometric isomers which gave the same mass spectrum (including fragments), so that ratioes could not bee determined. Only with the help of GC could we continue the project.
Other students at the University of Colorado had similar problems. To reduce the amount of substance needed, we students helped the technicians to develop a GC-MS. This was several years before HP GC-MS equipment was available, which seemed like heaven on earth compared to the home-built equipment. Anyway, I can´t imagine MS without some pre-technique, except if a single highly pure substance is to be analyzed or if separation is simple on MS.