Mhm, that got dark quite quickly O_O
@Panzercracker No offense, but your thinking ignores some things in the economic department, goblins here are (normally) obviously the equivalent to something like a small pack of wolves, economically it is total nonsense to send something armylike. The standard 4 to 5 people adventurer group is a bit arbitrary, we can agree on that, you could do 8 or 12 or 50 if you want, but there is a limit, first of all larger groups (liek ~50) need to do larger quests, because the reward would be too low otherwise, groups like this wouldnt form in relativly safe regions and quests for reaaally large groups would threaten the nation, so they would normally dont even pop up, because the real army would take care of national threats, at least outside of special threats like real dragons, which would need a small number of exceptional individuals anyway, because "smallfry" would stand no chance.
So, in the end a group of 4 seems small, but would make sense for small (1-3 day) and easy quests (which this normally would be, the goblins are only dangerous because of a leader that organizes them plus the fighting strength the dragon itself has, the quest is probably easily 20 times more dangerous then it should be even before the adult dragon comes in).
If we look at adventuring in fantasy in general groups with about 10-15 members would be probably more common then the standard 4-5 for the reasons you mentioned, better possibilities to split up the work of camp setting, hunting ect, but larger groups then 20 tops would probably not form, at least outside of reaaally high threat regions.