a little insight i’ve picked up over the last couple of months is that creatives and game developers are terrible at all the business and finance ends of things for the most part. Developing a title (especially new IP) will essentially just burn money until you launch (Unless of course your name is Chris Roberts and you sell virtual spaceships)
Sadly established publishers like EA, Sony, Microsoft and the like bring to the table is money and lots of it, with this money they will also bring in good things like purchases of middleware licences, marketing, access to larger development teams, etc etc.
The other side of the coin is that this “free money” comes at a price. That price is pressure, as the publisher will want a return on their investment. The pressure is usually what the indie devs/publishers try to avoid, but the bigger publishers will take creative control and lay down the hammer.