When the universal profiles were introduced way back in 2012, they got rid of the old user profile URLs when you click a username inside of a topic. This made it impossible to extract the User ID of every account inside of a topic without having to first compile a list of every unique username and then visiting the user profile of each unique username. That would have drastically increased the number of requests it would have taken to scan a topic for new usernames, and so Your Eliteness decided not to implement that type of fetching system. A profile fetcher could have also been a viable replacement (with a heavy punishment to any user that tries to fetch a profile that returns a 404 error), but Your Eliteness did not bother to implement this.
Without any way to fetch topics or user profiles, the only option to add new users is by doing it manually. I have tried my best to manually add users, but do not have the resources to keep up with all of the new accounts being created. About a month ago, a change was made on GameFAQs that now makes it possible to extract the User ID of every account from each page of a topic without having to visit their profiles. When you hover over a username, there are several dropdown options available. The easiest way to extract the User ID for each account is by using the HTML source code for the "Send PM" option, since that option appears on every account that posts in a topic. Using my GameFAQs username as an example, the source code of the "Send PM" option would look like this:
<form class="send_pm_3819007" method="post" action="/pm/new"><input type="hidden" name="key" value="[random value]"><input type="hidden" name="to" value="-LusterSoldier-"><a onclick="$('.send_pm_'+3819007).submit()">Send PM</a></form>
By using a regular expression, Your Eliteness could extract the User ID from the class attribute on the source code I listed above.