Judaism is not practiced in isolation. Integration into the Jewish community is an essential element of the conversion process. A person who keeps every single mitzvah but does not live within or take part in a Jewish community will not succeed in the conversion process. Judaism is not a religion alone; we are a people. Converting to Judaism is not simply about accepting our dogma or living in accordance with halacha. Actively integrating, making friends with, socializing with other observant religious Jews is part of the process.
Another important element is finding other conversion candidates with whom to travel this often lonely road with. Integration can be hard, and going through this process with others who are doing it as well, is crucial to both their success and maintaining the inspiration along this long journey.