The most disturbing thing about this saga is that websites that have no physical/legal/business presence in the UK are proactively geoblocking UK-origin IPs. Censorious governments have always been a thing since the beginning of the internet. Websites (especially non-corporate ones like 4chan or R34) preemptively surrendering to a foreign government that has no jurisdiction over them is what's new.
Many countries, including the US, claim jurisdiction if you are providing services to their citizens. Some claim jurisdiction if someone in that country sees your web page (ie you've now "published" it there).
You've been blissfully unaware, perhaps, but this has been a thing for a long time.
You have probably seen sites having sections of their TOS tailored specifically for Californian users- this is not that different.
I think the UK legislation here is hamfisted and very harmful, but the jurisdiction argument is nothing new.