[giantrobot]

MacOS 9 had a personal web sharing feature. The Apache server with Rendezvous/Bonjour was basically the MacOS X implementation of the same. For OSX it was literally a free mechanism to add web sharing.

As for the use case, in the classic MacOS days and even early days of OSX the system didn't ship with support for Windows file sharing. It wasn't until IIRC Jaguar (10.2) that Samba shipped default with the system. Web sharing made for a workable lowest common denominator for getting content off a Mac to Windows. With Bonjour (in Safari) you'll see all the shares on the local network segment.

Additionally since web sharing was just Apache it shipped with a bunch of the extension modules. I believe PHP was enabled by default so you could just drop a PHP script in your Sites folder for a dynamic page. CGI was also simple to enable because thanks to all the shipped modules.

Bonjour is decidedly a local peer-to-peer discovery mechanism. Even the packets have a short TTL so they don't route beyond local segments. It's far too chatty to be a WAN discovery system.

We ended up with cloud mediated connections because of NAT and UPnP hole poking sucks. Residential routers are really shitty in general. They also don't make port forwarding easy (or possible). So a host behind a NAT router doesn't usually have good options for receiving incoming connections. That's why we've got a bunch of NAT traversal protocols and need public hosts to mediate those connections.