It's a product whose largest cohort is designers or design-minded people. Them focusing on that as part of the product itself feels like a perfectly good use of their time.
No one said they were, I don't even think this font is available for use outside of are.na's product. This is about craft.
I think they said it pretty well themselves:
With Areal, Dinamo designed an updated version of Arial especially suited for Are.na, but which still honors the original. Stem thicknesses were streamlined, more characters added (), a monospace version drawn, dark mode functionality optimized. You probably wouldn’t have noticed these changes if you hadn’t read this statement. It’s possible you still won’t. But to us (Are.na and Dinamo) Areal’s existence is satisfying in the way that rewriting an entire front-end is satisfying. As stated in this text block from 5 years ago, “the reason you would create something is because you love it enough to see it exist.”
