Because as I’ve said before, 5v5 just doesn’t feel fun with 3 roles.
In 6v6, even in open queue you had more choices for your team. If you wanted to play 3-0-3 and go GOATs, you could. If you wanted to run Lucio and 5 Damage heroes you could. If your team felt they were fine on healing but weren’t securing picks, you could go 2-3-1. And if you wanted that good balance of having enough healing, damage, and tankiness, there was always 2-2-2. You could make your team imbalanced in some way (sacrificing durability for damage or healing, sacrificing damage for durability or healing, or sacrificing healing for durability and damage,) but you didn’t have to.
In 5v5, you have to. With 3 roles and 5 players, there’s no way to make that balanced team. Assuming you want at least one of each role on your team, you wind up with someone doing their role solo. You could get a single Tank trying to make space and peel and harass the enemy backline etc., but by themselves. You might have a single Damage hero trying to secure every pick, particularly now with the DPS anti-passive, meaning if your DPS gets picked all your enemies get effectively +20% healing (and they all get it if your DPS was trying to get someone else at the time anyways.) Or there’s the possibility of having one Support that’s trying to keep up 4 other people with the DPS anti-passive being sprayed around all over the place.
But you’ll notice that there is no balanced option. No matter which one your teams chooses, they must choose to be lacking in some department. This just feels bad to me as a player, feeling like I have to pick what handicap I want instead of feeling like I’m able to choose a balanced option.
5v5 also has the issue in Role Queue of having outsized importance on the Tank, since there’s only one of them now. In 6v6 RQ if a Tank goes down, there’s still the threat of that other Tank. But in 5v5 if the Tank goes down, the rest of the team follows shortly most of the time, since the entire Tank threat has been removed. Also since that one role has so much importance, it means when the Matchmaker decides to give one team a higher placed Tank that that team has an advantage. If you’ve got Team A with Gold Tank/Gold DPS/Gold DPS/Gold Support/Diamond Support and Team B with Diamond Tank/Gold DPS/Gold DPS/Gold Support/Gold Support, then Team B on paper has an advantage: since Tank is supposed to be so impactful to make up for the loss of a second Tank, that means that the Tank being better is going to be able to have a bigger impact on the match.
Also to a lesser extent, even without it being about Tanks specifically there’s a difference in the strength of getting a pick from 6v6 to 5v5. If 6v6 if someone gets picked, you’re in a 5v6. It’s not great, but you’re still somewhat okey: you’ve lost 16% of your team on that one pick, but can fight back. If you’re running 2-2-2, then you have at least one Tank, Damage, and Support left alive, so every role is at least still being performed. But in 5v5? Suddenly you’re at a 4v5. You’ve lost 20% of your team, meaning that the enemy team has more of an advantage in this situation than they would in a 5v6. Since it’s impossible to have at least two of every role in 5v5, this also means that with this pick there’s a chance your team currently has no Tanks, no Damage, or no Supports (if playing Open Queue, but in Role Queue there’s only the chance your team has no Tank.) One pick can completely eliminate a role in 5v5’s RQ, and due to how RQ is set up it’s the most impactful role, meaning it’s likely the enemy team can just clean up the rest of your team.
The more players there are on a team, the less one individual pick matters. As an example, consider a team size of 2v2 versus a team size of 1000v1000. If there’s one pick in the 100v100 match, you’re now at a 999v1000 state, which is hardly noticeable: the enemy has 100.1% of your forces. But if there’s one pick in a 2v2, you’re now in a 1v2 situation, which means the enemy has 200% of your forces. In both cases, it was just a singular pick. But with less people, each pick matters more and more. Each pick in 5v5 is technically more likely to lead to a team wipe than it was in 6v6, making the games feel more snowbally and deathmatchy.
These are all issues I have with 5v5, that aren’t really based around the balance of the game: they’re caused by the format. No amount of balancing will make a pick in 5v5 less snowbally than a pick in 6v6. No number tweaks in 5v5 will allow you to run a balanced comp, since you can’t evenly distribute 3 roles over 5 players. 5v5 makes the game more lopsided in team-composition, matchmaking, and gameplay, with no way to really fix them (though technically if matchmaking would actually wait until it found exact matches for each role to prevent two different SR Tanks from being in the same match it would at least address one issue, it would make queue times go up and since the stated reason for swapping to 5v5 was to make queue times go down it sounds like a non-starter.) So when someone says 5v5 can work but can’t address those issues, it just makes me continue to believe that 5v5 cannot work, on a fundamental level.