Measuring upload would require building out infrastructure to receive data streams with reasonable performance. That's nontrivially hard compared to the downlo

Measuring upload would require building out infrastructure to receive data streams with reasonable performance. That's nontrivially hard compared to the download portion, where they can use their existing CDN. Sure -- they didn't build out a fully featured internet connection monitor. But what they have built is a pretty good tool, especially for diagnosing Netflix or last-mile performance.