Here’s the crux…as far as the both the lore and basic value proposition of the game as a visit to warhammer-land go…that’s not necessarily actually a problem, it’s a reflection of the universe given form through player action.
As far what it has to do with the lore: Elite veterans being forced to carry or endure, in spite of incapable allies, as they’re all thrown into the same meatgrinder, is exactly what’s being promised in many instances. Nowhere does the game promise you a team of highly experienced and well equipped teammates executing well practiced mission runs for routine victory, it promises unrelenting tide of violence alongside other Reject prison scum wielding scavenged battlefield weapons with limited life expectancies, and many people will play as such.
Again, I’ll point to Deep Rock Galactic, like Darktide it’s a 4 person coop survival action shooter with four distinct classes and a variety of mission types. Doretta is a mining machine in one of the missions. It blows up at the end and its head is a separate part that can be picked up. Bringing the head back does absolutely nothing, doing so occupies a player while they carry it, it brings no reward, it triggers no dialogue, and forms no part of any mission objective. And yet, without fail, most every time players will bring the head and do their utmost to bring Doretta home. They will fail and lose missions over it they otherwise could have won, because of the game’s narrative and lore. These things matter. Doesn’t mean Ogryn need to go around acting literally stupid in Darktide, but if literally everything surrounding the game is screaming “disregard rational thinking, your life is worthless, death means nothing, go out with a bang”, people are going to feel less bad about taking on fights they may not be ready for than they would be in other games, and the game allowing them to do so isn’t necessarily wrong.
It’s also consistent with GW’s other products and games, where they drive home a “forge the narrative” message over encouraging tight and competitive gameplay. For years I was frustrated about problems with tabletop 40k’s rules until I eventually realized and accepted that the tabletop game was just a vehicle to sell plastic models and give people an excuse to play with their toys in memorable ways as opposed to a coherently designed and well written competitive wargame tailored for pickup/tournament play.
While yes, Darktide’s basic gameplay loop is exquisite, I don’t know any Darktide players that weren’t already 40k fans and as far as I can tell on Discord/these forums/elsewhere, that’s pretty ubiquitous. Lots of games have fantastic aspects or well crafted cores…and go nowhere, my Steam library is full of great games I’ve never played, but I’ve played some pretty mediocre 40k games. Fatshark’s non-GW games are a decade behind it and not really anything most people would ever recognize, certainly not anything I could say I’ve played.