smoboRaytekIt is the player's own responsibility to keep their IP private.
I have your IP address. You've scrimmed on my server, and your connection is in my server logs. It's not hypothetical, I actually have your IP. And that's somehow your fault for failing to protect it? Get real dude. Seriously, blaming the player for getting DDOS'd is ridiculous in TF2.
https://www.skial.com/sourcebans/index.php?p=banlist&advSearch=xxBOBSAGET_&advType=name
I don't know who this guy is, but he was griefing in a SKIAL pub in 2013, so his IP is on a database you can search by SteamID. You can just grab it. It's not even a permanent ban, but his IP is still up there.
You are right about IPs being very hard to hide since they are logged on basically every server, but that doesn't mean players should ignore basic safety measures to weed out the easiest exploits to get a user's IP.
1. Don't use IRC without protection (VERY important):
When you join a channel in most IRC servers, your IP can be grabbed with minimal effort. How to protect yourself differs from server to server, use google. A bouncer is the best protection.
2. Don't accept random skype/steam calls. Steam/skype voice calls are P2P so they can get your IP from this.
3. Don't click fishy links. Could be an IP grabber.
Just a little bit of common sense will protect you from most vulnerabilities, having to do further than basic efforts scares away most script kiddies.
For preventing server ddoses:
1. Go offline on steam (otherwise the IP will be shown in "view game info") BEFORE joining a server.
2. Don't use serveme.tf servers. They are great, but they are also not protected.
3. Server cvar "hide_server 1" so it doesn't show up in the server browser.