It’s not a coincidence at all - the donations/importance of their families dominated the holistic picture, and they were judged able to do the work, so they got in. It’s similar for a recruited athlete. And there’s no right or wrong to it - it’s just business, Harvard’s business. They’ve been admitting students for nearly 400 years, and they believe the collection of individuals they admit each year is the best they can get in order to satisfy many different institutional needs (apart from having a certain number of geniuses, these include funding, access and beating Yale at football, among lots of others).
Those institutional needs can change over time, as society and the law change, but at any given point in time, Harvard has a view as to which kids will deliver the most advantages for Harvard, and that’s who gets in.