Havoc generates 3 separate conditions per map for 40 hidden layers/modifiers of maps of varying difficulty. Even though it’s not the complete map pool, just one map has 120 variations of it that is playable and generated on a per player basis.
There’s no reason to grind out havoc aside from achievement hunting, and maxing out all weapons and such takes no time at all just playing the game, let alone speedrunning an archivum syckorax or enclavum baross in under 10 minutes.
The party finder may be imperfect, but it exists and is an easy way to filter these missions out of normal quick play (if that is really such a concern).
So, why not have a UI very similar to havoc mode, but make all of the modifiers selectable, even choose what level of havoc/hidden modifiers without having to worry about demotions, and choose up to 3 different mission modifiers per game. You could even have 1 specific modifier slot be related to maelstrom modifiers, from CIVI to Monstrous specialists, and after selecting all modifiers, you can place it into the party finder queue. If you did update party finder to support a lot more features, you could choose to blacklist certain modifiers and whitelist others, making it far easier to select which missions a player wants to join.
The only other reason I can think of is the misunderstanding that this would further divide the community. For one thing, map selection has always existed in this genre, and a lot of these games are still alive, including vermintide 2. From what I gather in hearsay and even during some of my active hours in the game, havoc is a near dead game mode that is only going to become more dead as time goes on, but quickplay as a functionality is completely fine, being able to find people of all kinds of skill levels in every difficulty and an active player count that regularly hits over 10k. You can still find players in a dlc-locked difficulty throughout the day in vermintide 2, a game with less active players and several separate game modes to queue from, and a modded realm with an active player base.
My last point is that Party Finder without this feature will probably become another abandoned ui feature that never gets utilized or expanded upon. Havoc in its current state is filled with achievement hunters and people who play for the difficulty, both of which are more likely to use the discord for a proper functional group. Both of these groups overtime will grow thinner, with people unlocking their achievements and abandoning the difficulty, and people finding no one in their free time or having found a new consistent friend group for runs rather than randoms. It’s clunky, it has terrible visual clarity, the filters are awful and inconvenient to navigate, and there are numerous bugs associated with it. People can pull you out of matches or groups because you mass applied to several groups hours ago looking to just get into one, and they finally played a mission, left, and it didn’t reset their list. It sometimes fails to show players in a lobby, taking upwards of minutes to refresh. Many people could not find matches at first because it had a default applied filter that people were not aware of. You can’t find specific builds from people, you can’t join a queue or set up a mass application to join a variety of groups with similar descriptions, you can’t join to fulfill roles or wanted classes, so everything is guesswork, from applying to people, to the people you accept.
It’s inconvenient in its current state as an unfinished, terribly designed system. No one wants to use it, it’s not fun to use, it’s only use is for only one game mode that people are very particular about when it comes to teammates. Just adding map selection will expand its usefulness greatly, and encourage making a more in-depth version of the current system in play. A system with a lot more clarity, more intuitive, better application, and hopefully a lot less buggy.