As someone on r/kurosanji put it, because their entire MO of Nijisanji has been to "churn out more livers and talents as that has always worked for them" with Hololive you feel like each generation debut, because of their timed releases, as well as the gap in release from one gen to the other, people are able to simmer down with them, get to know them, and the holmems also get to shine and get into the groove of streaming and also in the limelight of being a new generation, which is what Nijisanji lacks, and has been lacking for a good while now. Not to mention every single Holo gen, for the most part, feels like an event, like the release of a long-awaited movie or TV series, which is also why it shows in how many subs they get, so much so that many debut already at like 100K or so, easily, so much so even YouTube has to "stumble" their growth, and even think that, with their algorithm bots, they grow a little
bit too much.
Suffice to say, it also helps a lot that, both old, veteran and new holomems get to interact early with each other, as well as with fans, which makes the process of their debut and welcoming, that much easier in everyone's eyes.