Hacker news generally follows trends, and this is the current trend.

The discussion around coding agents nowadays is steering towards harnesses (which is probably a better description of what this is). "Agent" here is doing a lot of heavy lifting and has become a bit of a catch-all term to describe a model + harness + tooling + prompt + some other things that I've probably not thought about. The harness is a part that's being explored more as many believe it's where we can get some better performance out of the models.

This one in particular is from Vercel who provide a service to use models, so they have a vested interest in providing a harness.