With good positioning and situational awareness, good McCrees can and will pick off tanks. And as Blizzard has said themselves, he was never meant to have that capacity which is why he is getting nerfed.,
What I'm saying is that can be said of a lot of characters. Being out-of-line with design philosophy is one thing, and if Blizzard thinks it's too beefy then whatever, but me personally I don't see him as any more threatening than the multitude of other characters who can do the same thing only faster, better, or with more safety.
you are seriously underestimating mcrees overall stopping power considering he has a output of 840 damage in under 2 seconds WITH a grenade that stuns people. Mcree out DPSs every character in the game. Mcree is just a more powerful, less mobile reaper, if you are playing payload and 4 of your teammates is on the payload, Mcree is licking his chops at this moment while he flanks you, kills your flank counters and then continues to harass your team from behind when he gets back his grenade which then opens up opportunities for the rest of his team. These situations you keep coming up with have mcree going up against a group of people by himself. Your not going to be able to move the payload against a competent team with 2 people on the load. even then 2 mcrees flanking at the same time can take out 3-4 people while the rest of your team eats up the left overs. the team who can flank most likely gets the upperhand in the fight and mcree wins that battle everytime
But so can most characters. I know McCree's damage output is high if he can get it off, but 840 damage in 2 seconds is equivalent to what... 2 junkrat grenades hitting 3 people, which he can do from almost a full point away AND has more mobility? And McCree is only hitting one person, assuming the flashbang actually hits. And when it happens he has no stun or roll for what... 8 seconds? He can spend his entire kit to burst someone down, but then so can S:76 who also has sprint and a heal. So can reaper who can go invulnerable and teleport. So can Tracer who can blink in, buzz a squishy, and jump back out, and back in and out over and over.
McCree's selling point is fan bang. It's more valuable in the few cases where it works perfectly and he can get away, and otherwise is, imo, less valuable than the multitude of other characters who can do the same job but better and don't rely on an 8 second cooldown grenade to be a viable choice. He can break a tank, which is cool and dandy, or mow down a squishy target which I mean who can't? I mean shit, even Mei has better CC and can shut entire teams down from huge distances away, AND has a game changing ultimate, AND has survivability. The only thing she doesn't have is the range McCree has, but otherwise if we assume 2 seconds of free-firing because you've caught the opponents off-guard and they are somehow unable to react, then Mei has no trouble dropping a reinhart shield either. Mei has no trouble setting up for any number of plays.
If McCree is with a group against a group, then his value comes from the situation where other characters would be more effective in total. I'd prefer a Pharah take 2 seconds to lob 3 missles into the heart of the enemy team behind their tank and just outright kill half of them and neuter their push, or junkrat lobbing 2 grenades and a satchel charge both damaging and displacing them, or soldier 76 shooting a helix missle and unloading a clip into whoever, over McCree running in and killing only one person and then possibly dying or throwing one grenade and doing 420 damage because he can't afford to slam two hammers into it. Maybe that's just me, maybe I favor safety over raw throughput, but when I look at other characters who can do McCree's job but get away with it and only fall short in the absolute best-case scenario, I still can't admit that McCree is "broken" or even "overpowered".
He is a good character, a strong character, a good all-rounder, but not someone I'd pick over a character who has a purpose and isn't just the "best filler".