Dude, what Camoshark said. ZIP files are the way to go.
ZIPs at least not only incorporate the FLP files, but they also incorporate any voices we were to use. Because I am a soundfont user (and a heavy soundfont user at that), it also includes the SFs for easy reference. If I were to just stick the FLP there without all the bare bones of the project, people won't even give two hoots about understanding what it is I've done with the piece.
FL is the bread-and-butter of a lot of musicians here? Yes. FLPs should be accepted in Dumping Grounds? ABSOLUTE NO.