In China's case, it is a very well known and documented fact that heavy censorship is present. Of course if one thinks additional knowledge on that is useful enough to solicit wide user participation, that is certainly one way of thinking.
Censor lists can be slightly different on different networks. Also the exact addresses that are censored changes over time. The probe collects this data. "Everyone knows it's censored" is not data. There is a good chance that someone else on your network ran the probe recently though, if that's what you mean by your excuse.
The probe also collects data like the exact mechanism of censorship, the IP or domain it redirects to if applicable, the DNS server to detect if DNS has been redirected, and so on.
