::shrug:: There are many things that few amateurs understand. Few amateurs understand process gain. Few amateurs understand Fourier transforms. Nonetheless, many amateurs utilize FT8, which is based on these things. With mobile HF, the goal is usually to have an antenna, that is "less bad." It wonders me how much gain and directivity are indeed necessary to achieve practical communications. It is easy to build an antenna for 80m that is mobile and has -15 dBi gain. It is possible to build a "less bad" antenna that has, say, -8 dBi gain and a main lobe that is vertical. How much is good enough? http://kv5r.com/ham-radio/nvis-army-fm-24-18/ The army seems to think it is practical enough to be useful, or at least thought that at one time. Or perhaps they were just experiencing groundwave propagation and, as you suggest, mischaracterized it as NVIS. But if you can get reliable ~300 mile comms, maybe it doesn't matter much.