There is always a hierarchy regardless of whether the HR database reflects it or not. The HR database only grants a hierarchy legitimacy, nothing more, nothing less. Regardless even in places where there is a hierarchy you will see getting promoted means nothing unless you have influence with the powers that be.

In many ways these power structures are a feature of any large people operation. You just need to get used to them.

Things will be chaotic, but modern software development does some good ideas to the table to maintain order. Things like Agile, OKRs etc might not be perfect but they do help.