Because people don’t understand how copyright works.
In most countries any copyrightable work that you produce is automatically covered by copyright. You don’t need to do anything additional to gain that protection.
Most Lemmy instances don’t have any sort of licensing grant in their terms of service. So that means that the original author maintains all ownership of their work.
So technically what these people are doing is granting a license to their comment that allows it to be used for more than would otherwise be allowed by the default copyright protections.
What they are probably trying to accomplish is to revoke the ability for commercial enterprises to use their comments. However that is already the default state so it is pretty irrelevant. Basically any company that cares about copyright and thinks that what they are doing isn’t allowed as fair use already wouldn’t be able to use their comments without the license note. So by adding the license note all they are doing is allowing non-commercial AI to scrape it (which is probably not what was intended). Of course most AI scraping companies don’t care about copyright or think that their use is not protected under copyright. So it is again irrelevant.
Mostly dropping the analogy as it falls apart quickly once you try to talk about more specific details.
If you don’t want people to be able to call you then you can block incoming calls. This is sort of the like IPv4 NAT case, people can’t connect in (unless you forward ports). Or if you want to you can allow incoming calls. The choice is up to you now rather than being forced by a technical limitation.
Generally you will be provided a “prefix” by your ISP. In v4 this would typically be a full address. In v6 there are a huge number of addresses inside this prefix. In both cases how often the prefix chances is up to your ISP, but for v6 you can chance the suffix you use inside of the prefix as often as you want.
There are two main parts of “the phone book”. There is “Who owns this address?” and “How do I get to this address?” Both of these are basically identical between IPv4 and IPv6.
For “Who owns this address?” there is a global directory of assignments. This is typically done in multiple layers.
For “Who do I get to this address?” A protocol called BGP is used to advertise where an address is available from. So I may say “If you want to get to addresses 32 to 64 come talk to me”. This is sort of like in a hotel how there are signs saying which room numbers are in which direction. When two networks are connected they share this information between them to establish a “routing table”, so they know how to get to everywhere else on the internet.
This may look something like this:
Overall no single places knows how to get to every other address. But they know the best next step. So you don’t know where 17 is, but you know to send it to your ISP, your ISP doesn’t know where 17 is but knows that their partner tier 1 ISP knows how to get there, the tier 1 ISP doesn’t know where 17 is, but knows that it belongs to your friend’s ISP, your friends ISP doesn’t know what device 17 is, but knows that it is in your friends house, then finally your friends home router actually knows that 17 is your friends desktop.
You can sort of imagine this like delivering mail. If I send mail in Canada that is addressed to England, Canada Post doesn’t really care where exactly I am sending the letter. It just knows that it needs to forward it to Royal Mail and they will handle it from there.