The games they release are complete in them selves, and with 15-20€ dlces every ~6 months they keep the games fresh with new content.
People rarely complain that features are missing from their games until it gets added in a DLC. Then suddenly it’s a mandatory feature.
I’m pretty sure Crusader Kings III would beg to differ. As would Victoria 3 and, depending on whether 2016 counts as "the last few years, Hearts of Iron IV and Stellaris.
All of those are Paradox Development Studio originals that are considered classics and follow the Paradox model of more or less complete games followed by excessive amounts of expensive DLC…