Right. It also does DNS poisoning, URL word analysing, deep packet inspection, and VPN identification & blocking. I meant it only directly blocks the worst IPs, as opposed to directly blocking all external IPs.
I do wonder whether a US Firewall will be worse or better than China's. On one hand, the US is presumably less autocratic. On the other, we have 10x the defense resources.
It does some kind of automated crawling and blocking.
It has manual (as in human) blockers, who read content on Weibo and remove it.
It's still horribly crude, and fairly straight forward to route around but it's more complex than a simple static dns blacklist.