Mines of Moria™ has a surprisingly large amount of forced solo content. By that, I do not mean that you can solo it, or that it is too bothersome to find a group. The content is in an instance that you cannot enter in a fellowship. There are the six daily IXP instances, several chapters of the epic books, and steps in quest chains. Book Seven added six crafting instances, which are again forced solo. The three-man instances are forced small group content.
This is an odd way to train your players. I understand worries about people taking the easiest path, which is bringing too many people, but we already have hundreds of quests that people prefer to solo, with little evidence that they will bring six people to kill those eighteen orcs even faster. Do you want to train your players to spend multiple hours per day alone in instances? For non-hardcore players, that is their entire play session. It leads to the unfortunate effects seen with the opening of Book Seven: the outer areas of Lothlorien completely empty of orcs, as people solo them for the faction quests rather than grouping to share and speed things. You know that people around you are on the same quests, but we have been trained not to bother finding a group if it is possible to solo.
So far in Volume Two, there are three chapters that demand fellowships: 2.4.7, 2.5.5, and 2.6.8. I do not even want to count how many solo instances there are; I would guess at least fifteen. You can experience almost everything in Moria solo except the six radiance instances, and you need to visit those only if you plan to join the twelve-man raid. We do not need to force people to be alone even more.