The link isn't clicky, and I probably wouldn't click on it anyway so I don't know what context you are in here, but no, I don't think it's irrelevant.
It is very very relevant, and can cause all sorts of problems, which is why DH and I decided not to have children together as I have children from a previous relationship. My ex has another child, as he and the person he had the child with are no longer together, he has 50/50 residency. I know my dc sometimes get jealous that their younger brother has more time with their dad than they do, and I know the younger brother gets jealous because my dc get to do things (mainly holidays) that he is unlikely to be able to do as a child. My dcs brother also has two brothers on his mums side, and they get jealous because they get to do even less than their little brother as their dad isn't invloved at all.
I can only see this getting worse as they all get older tbh.
Blended families can be incredibly difficult, and only work as well as traditional family set ups for everyone concerned in very rare circumstances.