How useful are non-navigational radio beacons (i.e., for determining current propagation conditions and testing) nowadays, whether microwave X band, HF, ELF, sub-mm wave, etc., considering the advent of computerized propagation modeling? Is the scarcity of non-amateur radio beacons a result of there being less interest in ``exotic'' propagation modes (in favor of the current dominant practice of using microwave line-of-sight, whether terrestrially [4G, Wi-Fi, etc.] or via the artificial communications satellite) and the advent of high-quality, computerized models? Obviously there are plenty of niches for ``exotic'' propagation modes, esp. when it concerns redundancy in times of war, and I simply cannot imagine the models being comprehensive and accurate (imagine modeling the millions of meteors daily for meteor burst communications), so there must still be niches, just for propagation. Any insight? Thanks very much in advance.