It's a bit of a coin toss between the two options. The flair-filter system is one we've implemented before for the Ukraine Crisis. Both options have a lot of merit, but we decided to do a megathread for a variety of small reasons. One of which was that we felt the discussions in 99% of the immigration submissions were relevant to any of the other submissions. So we feel as though there is real merit in not only putting the submissions in one place, but the comments too. That way you can have a comprehensive discussion about immigration rather than 50 different small ones. If you compare that with something like Ukraine, there were a lot of stories within stories. Domestic Ukrainian political situation, domestic Russian politics, Crimea, the Donbass, the Baltics, the NATO summits, position of Western soldiers, the creation of the Eurasian Union, and so on: all unique narratives in their own right where the discussion is not immediately relevant to the wider discussion in the same way immigration sub themes are. So that's one significant advantage of a megathread in this instance. Another significant one worth mentioning is that flairs aren't often used. For instance, I would say that about half or less of the users read the sidebar, and about the same amount regularly read flairs. So they're unlikely to become aware of the fact that the flairs exist and are therefore going to continue to be unhappy with the way the subreddit is. It's essentially a communication issue, but one that we're unable to solve sufficiently. However megathreads are clearly visible and fit into the general way subreddits work seamlessly. A third reason is that I think there is a lot of benefit in actually cataloguing these immigration stories to try and get a holistic view of the situation. This is a similar reason to the comprehensive conversation reason I mentioned earlier, but instead of having a whole conversation it's about having a whole grasp of the news.

So, the reasons are quite numerous.