I get the sense that you and other commentators are putting a certain binary in place, and I'm not sure it's in good faith. Nobody ever said that you have to pick one particular place to be an expert in, and if you're not an expert there, you're not a good engineer. That's an absurd argument, but it's also not what is being said.
The truth is, you need to be good enough at all of the high priority parts of technical competency. Security, monitoring, performance -- sure, all of those are also extremely important. They're all places where unforced errors can be introduced that can and do hurt the business -- sometimes catastrophically or fatally.
With that said, to not recognize the evergreen utility of domain design skills is ignorant. You will never get the luxury to worry about security, monitoring, or performance if you don't build the state machine that makes the right outputs out of the right inputs because you will either never sell it to a customer, or lose that customer when they choose a competing solution which actually does what it's supposed to do.
It's not true that everything is equally important. I think that's a myopic way to look at software development without considering the business impact of key crucial areas where software design and maintenance intersect with stakeholders.