The Chinese system (and now the UK's) does not overly concern itself with ensuring every possible route through the Great Firewall is blocked--after all, geniuses gonna be ingenious. It merely suffices that the overwhelming majority cannot do this easily, and the technically adept live in fear of the consequences of their clearly pre-meditated actions. The censorship, and the chilling effect, is in the general drag; no need to close down every last loophole.
If John Allsup is right above, all that is required to get around this is "a LAMP stack somewhere on the internet" and some code. What percentage of the population are capable of actually doing this in practice? Taking say, the desktop share of Linux/BSD as a proxy for this, which is probably an overestimate, given the ease of installation of modern distros, that's fewer 3% of all internet users. A repressible minority? The UK government evidently thinks so.