People familiar with the AD&D 2nd Edition supplement for “Spelljamming” are immediately aware that this addition to the game can be a tremendous amount of fun. It can also be ridiculously off-balancing to any average campaign. For instance, how quickly players can travel from point A to point B by using a spelljammer. To put it into perspective, Frodo and Sam could have made the trip from the Shire to Mordor, and back, in about a day. For earthbound adventures, being able to zip about at ungodly speeds just takes a good deal of the fun out of a quest, by reducing it to little more than a quick errand.
That much said, Spelljamming does exist in the setting in which Slothjemia is placed. The mostly goblinoid nation jumped in to Spelljamming with great enthusiasm, and discovered to their dismay that they were in way over their heads. After a number of misadventures, things settled into a more manageable state, and while there are a only a handful of Spelljammers in the Imperial Navy, and Slothjemia does not possess much in the way of off-world colonies, there does exist a thriving trade with the various powers that control swaths of open space.
For story purposes, therefore, it should be remembered that as powerful as Spelljammers can be, they are almost always tied up doing something else. To allow for any other possibility risks tossing the world into chaos and imbalance. Sometimes an earthbound conflict just needs to find an earthbound solution.