Then don't talk to them on a public Mumble/Ventrilo/IRC server without adequate precautions.
Most MMOs & online games offer an in-game chat client that does appropriate cloaking & is also moderated (so an offender risks a ban if they engage in harassment). Nobody is forcing OP to invite these people onto his VoIP server.
It's not a real practical problem – and I'm not sure why we're pretending that it is one. Let's clearly state what the problem is: OP wants to play MMOs & online games against potential threat actors who may DDoS and/or doxx them. Which is why they simultaneously also want to shield their identity from them. An analogy would be somebody who wants to play games with the neighbourhood meth gang while not wanting to get stabbed.
This is not safe or reasonable behaviour. Even if these people lack a client IP, a motivated attacker can piece your identity together from what you say and/or post eventually. Discord just makes that a bit more difficult at the cost of you handing over PIID of greater importance.
The "threat model" of OP is the consequence of a wrong usage pattern. You keep your identities separate. If you're in a high-stakes environment where being DDoSed or attacked is an actual threat, you compartmentalize that identity adequately by going through a proxy, VPN, TOR, I2P, or using a different medium altogether. Fortunately, unlike other services, this is extremely easy with IRC since the identity is just a nick, and nothing prevents one from having as many identities as needed.
This obsession with having a single centralized identity where some vendor is trusted to painstakingly guard the linked PIID is misguided, unsafe, and harmful. Discord will fall prey to a data exfiltration attack eventually, and affected people will only then realize that this trust was misplaced. The fact that people are comfortable giving Discord their phone numbers while being worried about their client IP being exposed on IRC is baffling.
> I'd rather have Discord some user data that I'm consciously putting there instead of my enemies from the game DDoSing/Stalking me
Security by obscurity is not a real solution. If you have a public IP connected to the internet, you will be subjected to attacks and port scans either way.
Configure your network and firewall correctly and ensure no ports are open instead of trusting the false sense of security given by some proprietary vendor who has your data.
> sounds like: go put effort and decrease your UX.
"UX" is subjective. For me, Discord has horrible UX, with its flashy, slow, obnoxious UI and its incessant cacophony of tips, "new feature" notifications, and advertisements for "Discord Nitro".
Putting in the one-time effort to configure an IRC client (and making it "fancy") seems worth it to me instead of having to continually put up with Discord's whims. At least there is no threat of enshittification with this approach. "IRC Nitro" will never be a real thing. With Discord, you can never be sure. Elon might just decide to buy it on a whim and rename it something like "XDickswords" if he feels like it.
Integrating a Jitsi bot into the channel solves this.
> Good text chat (images, code snippets, emojis, reactions, etc)
All possible with good old web linking. Link to an image host, a pastebin, or a file host of your choice. Many IRC clients support inline display of image/media URLs.
All major IRC clients and servers support UTF-8 as well, so emoji away.
> Streaming Video (!!)
Jitsi (with a bot) or web linking.
> File share
Web linking.
> Robust bot integration
Quite possibly one of the strongest arguments for IRC. The protocol is well-documented, and it's very easy to write an IRC bot.
> Lack of security problem unlike the self-hosted alternatives have.
Also lack of transparency. The self-hosted open alternatives are auditable and can be inspected. Nobody knows what Discord does with user data or what security issues exist.
> Push2Talk - this is also important, I dont understand how e.g Teams dont have this shit.
Your (possibly self-hosted) Jitsi instance already has this.
> One account between all servers with ability to customize your identity
Until you get banned/blocked for some arbitrary reason, at which point you might as well start over, since everything is gone.
tl;dr: Web linking + some bot integration and client affordances solve all these. This is how the web is supposed to work.