A depositor is not the customer banks are chasing. It's the businesses who want loans and financial services like M&A and IPOs.
Their competitive advantage is not in their software at all. It's in their relationships. The software helps them scale to large numbers of depositors. That's all.
It's not pricing. As a consumer, it always seemed like the largest banks tended to be relatively non-aggressive on their rates. Isn't "we have economies of scale and pass the savings to you" the classic competitive play?
It's barely, if at all, public facing apps/websites. Okay, you've all got a branded app, you've all started offering Zelle, and you all let me take a photo of the (average of) five paper cheques I recieve in a year to deposit them.
It feels like for a while it was the vague promise of "we've got the largest network so you don't need to worry about finding a machine." A concern largely mooted by smaller banks refunding out-of-network fees and credit union networks.