I’ll answer it anyway – as with net neutrality, the issue is pretty much moot because the different legal systems in place discourage or outlaw the behaviour that these rules are needed to address in the US.

However, section 230 disappearing in the US will have a widespread fundamental effect on the way the internet currently operates, as anything that operates from the US or has them as a major commercial target will need to make some significant changes (and that’s a lot of them). This may or not be good for everyone else in the long run, but it will affect everyone as they try to adapt.

"Most other countries did not have rulings as dumb as Stratton v Prodigy to make them need such a law."

It’s not even really about the ruling specifically, but the way legal systems are set up. While the US has a focus on individuals suing for pretty much anything, other legal systems have different attitudes baked in, which naturally don’t allow for some random 3rd party to be sued for something they didn’t do. If you can’t sue company X because person Y did action Z on their property to begin with, there’s no need for a section 230 to spell it out.

Same thing with net neutrality – effective regulation and strong pro-consumer protection laws mean that there’s no ability or incentive to abuse a lack of net neutrality in other countries, and effective competition means that most companies won’t try even if they technically could. Because these are relatively weak in the US, net neutrality has to be encoded in order to prevent abuse.

"One could argue that it shouldn’t. But it certainly will, given how many of the services you use (such as Techdirt) are located in the US or depend on US infrastruture."

Exactly. For example, if section 230 means that Amazon are going to be held directly liable for things that happen on AWS, they can just make it so that US regions are walled off from the rest of the world and apply different standards. But, that affects a huge number of sites that are currently hosted on those regions and would require some significant changes on the part of those other countries. Similarly, if they are going to be held liable for user reviews, they can just disable them from amazon.com without affecting the rest of the world, but the infrastructure is shared to such a degree that they might end up just disabling it for everyone, even though there’s no liability outside the US.

Those are just the simple things, for a company that already has physical business presence and datacentres outside the US. But, then, what about all the businesses that don’t but are still used by the rest of the world?