If you want to use Vermintide 2 as an argument, why does Darktide have not nearly as much DLC as that game despite being out for nearly 3 years? The answer is that VT2 content is simply way easier and less costly to make. They had to put over 2 years worth of knowledge and resources from Darktide into Arbites alone.
Vermintide 2 had a new enemy faction only a year after initial release. Within 3 years, VT2 had 5 more careers, one more enemy faction, a new gamemode and several mission expansions. I'm probably missing more.
Within 3 years, what did Darktide get? Arbites and Mortis Trials I guess?