One might be confused regarding how a guild could find themselves in this circumstance in the first place; after all, if they don't have promising rookies, they just shouldn't buy the contract for the dungeon from the association.
The issue arose from the duties of official guilds. While it was true that the standard process was guilds paying for exclusive access to dungeons, it was not the only way they could gain entry into one.
The second method was to be instructed by the association to clear it. The contract between guilds and the association stated that the latter could give a dungeon to the former, which had to be cleared. Naturally, such dungeons were the ones that had annoying clear conditions and were evaluated as 'too much trouble for little return,' and as a result, no guild wanted to buy it from the association.
