Ubisoft originally advertised The Division 2 as having matchmaking for every activity which presumably included raids. Now that doesn't seem to be the case as Dark Hours will not have the feature and the community is not having any of it.
Ubisoft and Massive Entertainment have decided to exclude the matchmaking feature from The Division 2's first raid for some reason. It would be a problem in regular four-player activities but it is a bit of a disaster for Dark Hours which will need double that number.
The Division 2's social media, as well as its subreddit, went in flames after the announcement since almost anyone who groups up with other players relies on matchmaking to do it for them. However, one particular sentiment seems to be the driving force behind the outrage - casual players are afraid they won't be able to find teams at all.
Having a look at that confirmed the lack of matchmaking hints that Massive wanted players to give Dark Hours a shot with players they know first. Considering that the developers The Division 2's raids will be crafted with hardcore gamers in mind, casual players may be looking at the wrong bit of content as it doesn't suit their tastes.
Still, while encouraging clans to compete for the coveted achievement of being the first to complete the raid as soon as it launches, it wouldn't hurt to have actual matchmaking for those without raiding clans.
World of Warcraft used to be without matchmaking for 40-player raids and it was doable but The Division 2 is much more instanced which poses an additional challenge in finding a team for Dark Hours.
Given the amount of pressure from the community, Ubisoft and Massive will likely add matchmaking in the future but it's dubious whether it will be of any help - chances are the players who go through matchmaking will fail repeatedly and inevitably ask for the raid to be watered down.