This reminds of edonkey, a filesharing program launched in the year 2000. A deficiency in the protocol results in clients on a ip with a zero last octet being unable to receive incoming connections, which means clients can exchange data with fewer peers.

I believe that there is still some use of ed2k protocol by people using eMule. Torrents won but it is still around.

As far as I have noticed it has been rare for ISPs to give out ip addresses ending in zero since the early 2000s.