The answer is simple. There’s only 1 tank. People claim that they like it, because there’s less shields to shoot at. And how they enjoy the much faster pace of the game, and yet those same people in other posts claim they hate how certain heroes (e.g. Sombra, Sojourn, Zarya) are dominating their games. Mind you, I’m even someone who hated those 3 in my games. But, I also wasn’t someone claiming I enjoyed 5v5.
Here, let me make things a bit more easy to comprehend for you all. You see in a 6v6 scenario, you had 2 tanks, 2 DPS, and 2 healers. Usually a main-tank and off-tank. The main tank held the front line, and made space. They were the play makers essentially. Your team fight enablers. Where as your off-tank acted in synergy with your main-tank, and also would PEEL for your healers. If your healers got flanked, your off-tank’s job was to stop what they were doing and defend. Which ultimately is why heroes such as D.va was such a high pick in higher ELO’s. Not because Asian gamer girl with giant robot.
Now then, let’s look at OW2. You have 2 healers but 1 tank. If your tank is holding the front line, and your back row gets ambushed/flanked? That pesky: Genji, Sombra, Tracer, etc. starts their shenanigans? Your supports and back row are screwed the vast majority of the time. Why? You have no off-tank to peel, and take that pressure off.
Oh, you could have another DPS try to help you. But, what are they really going to do at 200HP besides getting slapped up? Resulting in the supports now having that much more of a harder time now keeping your tank (you have 1) alive along with everyone else. And you know what that means. “Where are the heals!? Our healers suck! Omg, the healers are throwing!” Do you get it now?
By people complaining (it was the DPS specifically) of OW1’s team composition, they essentially created 1 of the primarily hells that everyone now in OW2 is experiencing. And ironically enough, they are STILL complaining about in the posts we see today.
Out of curiosity for the entire community, don’t you think it’s a bit odd how a lot of the hero kit designs are meshing in OW2 compared to OW1? And how absolutely busted and broken certain combinations are now? With little to no counter-play, because people wanted a faster pace and more offensive game? Isn’t it strange how a Roadhog or Zarya can now go into a game, and just tear groups to pieces up? Or a Sombra or Reaper? You didn’t really have these problems in OW1. Well, you did (specifically Reaper and Sombra after certain buffs that were quickly removed after being given in OW1), but it was nowhere near how awful it is now.
So, think on these things. The next time that those of you who support of 5v5 are in an uproar about certain things happening in your games, that seem ultimately out of your control? Whether it be: Zarya melting folks, Sombra bullying your bac-row, your supports getting mushed? Think in how strongly flawed the request of 5v5 is. There’s a reason why polls on Reddit, and the vast majority of those of us who played OW1 prefer 6v6. Overwatch (as in team PvP) was NOT designed for 5v5.
Side note, take note at how both Jeff Kaplan AND Geoff Goodman left Blizzard. And ironically enough, they both dealt with hero and overall gameplay design and balance. You could say what you wanted about OW1’s balance (and yes, it had some terrible formats like GOATs for example) — but it was never this atrocious.