Many of the IRC networks offer a "cloak" if you register your nickname, and of course it's trivial to connect via a VPN or via Tor (if your network allows it).
Side-note on the cloak: You'll want to make sure you're identified before you join any channels, or everyone will still see your IP. The best way to do this on networks that support it is to use SASL.
Cloaks apply uniformally but will not mask the last bit of your reversed hostname. So it might leak info about your ISP or region but not your full IP.
What you stated is true of vanity vhosts though. Which will mask the whole record only if you’re logged in. :)
IRCds such as InspIRCd and UnrealIRCd speak of cloaks in the sense of user mode +x, commonly set on connection, which scrambles an incoming user's hostname/IP address to e.g. hidden-5npgt1.iinet.net.au or hidden-qjia2j.ncp0.j4h4.014d.2804.IP.
Freenode, nota bene the largest IRC network right now, uses cloaks to instead refers to a special format of vHost[1]. It does not offer Unreal-style cloaking.
I imagine this difference in terminology is what's prompted this exchange.
Back in the days I had to pay extra for a bnc/bouncer service (similar to a proxy), now most IRC networks offer vhost automatically, but I assume it's a bit less secured since the IRC networks themselves still know your real IP address.
It's not really possible for a server not to know the clients IP address though, so I think this is fair.
I do see what IP you're connecting from, but that information is limited to me only, and it's not like I care unless you're doing something very harmful to the service in which case I would ban you based on IP most likely.
Who really cares in this day if anyone knows your IP? It's not like that many of us are running servers from our home connection and thus vulnerable in some particularly pointed way. Behind a NAT you're pretty much fine unless some nation-state is out to get you.
You haven't used IRC much, have you? Maybe it's become a more civil place, but years ago exploits and DOS attacks over some stupid dispute were common.
It depends, most require you to register first before your IP is hidden, just like Wikipedia. In both cases, it's so the mods at least have some kind of tools to (hopefully) identify who a person is.