Distribution.

The reason for this blog post is "recruit engineers". Not every engineer is going to visit blog.airbnb.com, but presumably a lot of them are already on Medium.

They even close the article with,

> We continue to solve interesting problems around LTV every day (and as more insights come up, we’ll keep sharing them on our blog). Can you see yourself making an impact here? If so, we encourage you to explore the open roles on our team.

These blogs are always about recruiting.