It's basically impossible to prevent people from using VPNs without some serious governmental control over every telco - which of course may be the case in the UK, but I don't think a site operator can be held liable for that in any sane way.
Most of these features were available in Scala and Clojure 5-10 years ago - even though OpenJDK claims that they took these features from ML, I'm glad they are catching up to others in the JVM ecosystem.