it depends on what those other orgs want.

Not being able to do business in (or, depending on how serious they are about enforcement action, visit) the UK is actually pretty constraining. It's understandable if other companies decided they would prefer to find a middle ground that lets them provide one face to the US and another to the UK, or even that they're not interested in 4chan-style maximalism and found it non-onerous to comply with the UK asks because they're pretty in-line with the site's existing standards (I'd have to see the list of sites that complied to have a real opinion on that part).