"If you are in the EU, you are not allowed to use this website." Pretty much the same solution for kids under 13 years of age (which is to say, they of course still do use these sites, they simply lie about it which shifts the burden...)
Are you comparing it to age prompts? Those were way less effective than IP based geo blocks. Since GDPR, a lot of, maybe even most of the time it's not worth the effort to reload the page through a proxy. Especially for stuff linked to me by social media.
