They're not just nerds, they're power users. These are different things.

Pretty much everyone is a power user of SOME software. That might be Excel, that might be their payroll processor, that might be their employee data platform. Because you have to be if you work a normal desk job.

If Excel was simpler and had an intuitive UI, it would be worthless. Because simple UI works for the first 100 hours, maybe. Then it's actively an obstacle because you need to do eccentric shit as fast as possible and you can't.

Then, that's where the keyboard shortcuts and 100 buttons shoved on a page somewhere come in. That's where the lack of whitespace comes in. Those aren't downsides anymore.