Again. YES. If you've got a smart phone you've got a good enough field recorder.
We've got all this fancy synthesis now which is great but this method, I think, will stand the test of time. Overall probably a less CPU heavy method as well. If I'm trying to get a really dense creepy atmosphere I might start by making a project with just time stretched samples and FX...doing an arrangement almost as if I'm making an ambient track, bounce that, then do the rest of the work in an entirely different project. Bounce all the stuff from the first project to audio.