[digi_owl]

In technical terms any computer can be a server. Just look at the BBSs that was run out of C64s and similar back in the day.

But a server that can't be reliably reached is a useless server.

And the BBSs worked back in the day because dialing the same number days, weeks, even months inbetween would lead you to the same BBS if the computer was still running.

A domestic internet connection is simply not reliable enough for that. Yes, if nothing happens electrically at either the customer or ISP end the IP will remain for some time. But have a power failure and it is likely that the IP will be reassigned. And that random aspect, that sometimes you can retain the address for months, and other times get it changed within hours, do not help.

[echochar]

I agree firewalls and NAT are a nuisance, and today's internet is not one iota as cool as the BBS days. The nuisances introduced by "ISPs" have hindered but in the long run have not stopped reliable peer to peer internet. I will not name the commonly known examples lest it divert the conversation.

There are a variety of workarounds for dealing with firewalls and NAT, and after years of using them "experimentally", I can attest that they work reliably, at least for me. Some of them are well-known, some of them are commonly used, others are not.

If IP addresses assigned to so-called "reliably reached" servers were as static as you imply in practice, there would be little need for a mechanism like DNS. (And I'm not saying there is, just pointing out that there are a lot of folks who believe IP addresses must be able to change without notice.)

In my experience, domestic internet connections with "dynamic" IP addresses are "reliable enough" to do some "useful" things besides simply partaking in the "calf-cow" web.