While you may have point, Coco is a step ahead of the curve because a) she continued to maintain her alternate internet identity even after joining Hololive, and b) it quickly became widely and publicly known, to the point that it was functionally an "open secret". This means that she didn't have to put any work into getting off the ground; she was already there and leaving Hololive basically meant that she didn't skip a beat at all. The only Japanese Hololiver who can say the same is Noel; her identity as Canan is widely known, she still releases videos on her other channel, and her sexy ASMRs are still bringing in dough. She could conceivably leave Hololive tomorrow and be okay. But most of the other Hololive stars have no such guarantee. For many of them, their identities are not as widely known, if they are known at all, they have nowhere near Coco clout or fanbase, and they would have to rebuild their internet persona from scratch, and they couldn't just come out and say "Hey, I used to be with Hololive". The Indonesia Hololivers are even more obscure than the Japanese ones, and I think for a few of them, their identities are still virtual unknowns.
Ironically, I think the Hololivers best prepared to move on from Hololive are the English ones because all of them already have pretty well known independent personas: Karen can just focus entirely on being Demondice (it helps that she never dropped that persona, even as Calli), Kiara still has her Keekihime Youtube channel (though I don't think she's posted anything to it in months), Gura can easily revive her Senzawa persona, and Ame could probably just go back to being Sachiowo (though she was probably the least successful on the HoloEn girls prior to joining Hololive). Ina didn't have that prominent an internet persona prior to Hololive, but she's already a professional artist, so she could just go back to focusing on that full time.