Why do you think the penalties for perjury and contempt of court are so extreme?
A large chunk of society hanging together and working relies on impartial but powerful judicial systems. It's one of those thin edge of the wedge situations. We don't want a system where people flout court rulings even if it's just about a notice on a website.
Also note: British judges and prosecutors are not elected by popular vote -- they're appointed from within the system on the recommendation of their peers. So they're heavily invested in the authority of the judicial system itself, rather than in dancing to the electoral campaign paymasters' tunes.
A large chunk of society hanging together and working relies on impartial but powerful judicial systems. It's one of those thin edge of the wedge situations. We don't want a system where people flout court rulings even if it's just about a notice on a website.