Willie the Duck
Hero
Hobgoblins also have major nation states in the Kingdoms of Kalamar setting, if anyone remembers that one.
As to the Realms, I think this is more of a systemic problem than specifically picking on hobgoblins. A lot of the game settings when they got their initial boxed sets in late 1e had a lot of empty spaces at the edge of the map. Maybe not physically at the map's edge, but there were always 'empty' spaces for you to put 'something.' I think that's where all the orc and hobgoblin lands were supposed to be, along with bandit kings, places where the free hypogryphs roamed, where the uncharted forests were that you had to travel to for the plot hook, etc. With each edition, expansion, Volo's guide to ____, or novel, the writers have been filling in those empty spaces. That's fine for some stories. You can still have ancient ruins just off the beaten trail 80 miles from Silverymoon. You can still fight the Zhents or clean up one of the abandoned Dale cities or go down to Chult to ride dinosaurs. But there isn't really a lot of good places for petty kingdoms, tinpot dictators, or the like (human, orc, or hobgoblin) except in truly remote places it is hard to get your PCs to go to. It is a conundrum I usually address by warping my FR maps ("You know those two nations who share a boarder, but aren't at war? That's because there's actually a 500 miles stretch between that the printed map does n't show. It's a demilitarized region that's fairly unsafe and full of adventure opportunities.").
As to the Realms, I think this is more of a systemic problem than specifically picking on hobgoblins. A lot of the game settings when they got their initial boxed sets in late 1e had a lot of empty spaces at the edge of the map. Maybe not physically at the map's edge, but there were always 'empty' spaces for you to put 'something.' I think that's where all the orc and hobgoblin lands were supposed to be, along with bandit kings, places where the free hypogryphs roamed, where the uncharted forests were that you had to travel to for the plot hook, etc. With each edition, expansion, Volo's guide to ____, or novel, the writers have been filling in those empty spaces. That's fine for some stories. You can still have ancient ruins just off the beaten trail 80 miles from Silverymoon. You can still fight the Zhents or clean up one of the abandoned Dale cities or go down to Chult to ride dinosaurs. But there isn't really a lot of good places for petty kingdoms, tinpot dictators, or the like (human, orc, or hobgoblin) except in truly remote places it is hard to get your PCs to go to. It is a conundrum I usually address by warping my FR maps ("You know those two nations who share a boarder, but aren't at war? That's because there's actually a 500 miles stretch between that the printed map does n't show. It's a demilitarized region that's fairly unsafe and full of adventure opportunities.").