I still clearly recall the first time I stumbled my way through the Deadmines in vanilla World of Warcraft with four random dumbasses I found in zone chat. At the time, it seemed like a transcendent experience. These polished, five-player instances were about as close as I'd gotten to playing Dungeons & Dragons with friends on the computer. But now, 21 years later, that dream has turned into a bit of a nightmare called Mythic+, largely due to the toxicity that Blizzard hasn't done much to effectively combat.
You can still run Normal and even Heroic difficulty dungeons relatively stress-free in retail, but they don't present much of a challenge nor reward you with loot that's worth your time. If you're really interested in the five-player experience – which I would still say is the sweet spot at which WoW's mechanics truly shine – Mythic+ is where you're supposed to end up.
In case anyone doesn't know how it works, Mythic+ dungeons are upgraded, harder versions of max-level five-player instances that can scale in difficulty from a +2 all the way up to a +12 version. Each level adds more enemy health and damage, better loot, and certain levels also introduce extra mechanics. To run one, you need a keystone, and you'll get a +2 keystone every week for completing any regular Mythic (often called "Mythic 0") dungeon.
The wrinkle comes in with how keystones are upgraded and downgraded. Mythic+ dungeons have a timer, and you can upgrade your keystone to a higher tier by beating that timer. The more you beat it by, the higher the upgrade. Finishing the dungeon after the timer runs out is called "depleting" a key, which downgrades it by one level. This whole system makes some sense, at least in theory. You should end up with the key level representing the maximum difficulty you can handle. However, in practice, the way Mythic+ is designed is directly responsible for fostering toxicity.
For one thing, when a timer is the only metric of skill that matters in terms of rewards, every dungeon becomes a speed run. This is especially rough on tanks, since you're expected to set the pace and know the optimal routes through trash, which is why I haven't played a tank in WoW in almost a decade despite being an altoholic with seven or eight max-level characters at any given time.
This can be a fun way to play occasionally. But especially if people are expecting to get a +3 key upgrade, which requires you to beat the timer by 10 to 15 minutes and have minimal deaths (each one takes time off the clock), it reduces the tolerance for mistakes to a level that I think actively hinders anyone's quest to get better. Mistakes are how we learn, after all.
I don't think Blizzard intended to create this kind of an environment. But if they can't take a step back and analyze why it is the way it is, the problem won't ever get better. We have this high-end progression system in which speed and perfect execution are prioritized over other skill metrics; any misstep could mean wasting someone's time and denying them greater rewards with no chance of trying again, and little or no consideration is given to helping anyone learn to get better. You're kind of on your own there.
Now, I'll pause to say this can all be circumvented if you have a regular group of four real-life friends or a chill guild to run keys with. That's the dream, right? The problem is, at this point in my life, I just don't have the extra time or energy to devote to a progression guild. At worst, it can feel like an extra job. And even at best, it's another demand on my social battery. Communities like No Pressure have formed to connect like-minded players who want to run keys without getting yelled at, and that's great. But it's relying on the community to solve a problem the developers created and I think they could fix.
My primary suggestion would be to look at games like Final Fantasy XIV and add some kind of social currency like accolades or commendations. I'm far less interested, personally, in someone's seasonal Mythic+ rating – which is purely an expression of skill – than I would be to see that they had been frequently rated as "Friendly" or "Helpful." And I'd even go as far as to advocate giving cosmetic or mechanical rewards for this. Can you game these systems if you really want to? Sure. But I think it's better to have them than not.
The other suggestion I would put forward is to, if not do away with the timer, at least introduce some alternative to it. I love watching speedruns. I'm not against rewarding players who want to go fast. But it's terrible for learning, it doesn't work great with PUGs, and it incentivizes specific playstyles that aren't necessarily directly correlated with player skill.
There are other ways you could judge how good a player is and if they're ready for the next level of key. And there are much better ways to foster learning. Everyone's always complaining about how no one knows how to use their utility buttons, so maybe award points for that which, added to your time, contribute to the "final score" for the dungeon. Give us a "combo bonus" for killing a whole bunch of trash in a short time window, or without leaving combat. Let healers build up a streak for getting through multiple bosses with no deaths. At the very least, have some backup mechanics that acknowledge you played well even if you made some mistakes and failed to time the key.
It's easy to blame the players for being toxic. And I'm not going to let them off the hook completely. But I think it's also unhelpful to ignore the ways that game mechanics can incentivize bad behavior and disincentivize good behavior. And Mythic+ does both, at least in a pick-up group setting. It's a too often neglected horizon for MMO design to include prosocial mechanics and identify antisocial ones, and if Blizzard wants WoW to stay strong for another 10 years, it's one they would do well to explore.