Hm, now that you've said "thousands of explorers", I thought I'd take a look at the actual numbers. Turns out that half of the GMP fan fiction regions' names came from one person, and only 11 out of the 58 names came from outside the GMP team. (Plus three regions were from real life, and one from Frontier.)
If you'd like a specific breakdown, here you go:
29 by Erimus Kamzel, 9 by Corbin Moran, 5 by Andrew Gaspurr, 2 by Akira Masakari, 2 by Drew Wagar, 2 by Kancro Vantas, 1 by Allitnil, 1 by DioStar50 & Erimus Kamzel, 1 by DrNoesis, 1 by Edelgard von Rhein, 1 by Murishani.
In the end, six region names were added to the game by Frontier, from Erimus Kamzel and Corbin Moran. Plus the same amount of systems. As far as I know, no other exploration community's names were included.
Something else that's also worth mentioning in my opinion: when Frontier placed the various NSPs over the galaxy, many of them were placed at GMP POIs. Not counting obvious ones like large nebulae, of course.