From Bastion and Torbjorn to McCree and his Fan the Hammer ability, it appears as though certain members of Overwatch's audience have a keen ability to detect what is "overpowered" in the game and what is not. The next hero on their proverbial chopping block is Widowmaker, one of Overwatch's most prolific characters and the only traditional sniper in the game. Of course, this begs the question of whether or not she really is overpowered compared to the rest of the heroes.
On paper, Widowmaker doesn't play too differently from sniping-based classes in most other games. By default, her rifle does 13 damage per shot in its automatic firing mode, 15 damage per shot when scoped in and uncharged, and 150 damage per shot after being scoped in for a second. These numbers are doubled upon a headshot, meaning that the maximum amount of damage Widowmaker can do in a single shot is 300 damage.
As a result, all but six of Overwatch's 21 heroes can be killed in a single headshot. Alternatively, Widowmaker can simply shoot most of them in the body once and then follow up with another slightly less powerful shot, but this would give the intended victim just under a second to react. This, combined with her ability to use her grappling hook to escape direct combat and the fact that one of the healers (Zenyatta) can be killed with a single (fully charged) bodyshot, seems the basis of most of the complaints against her.
From a realistic standpoint though, not every Widowmaker in every match is going to have 100% accuracy, and that's not including all of the damage mitigation and movement options that are available in Overwatch. But let's say that Widowmaker is going to be nerfed in a way that appeases those who are asking for a nerf, whereby either her rifle takes longer to fully charge or her weapon does somewhere between 100 to 149 damage on a fully charged bodyshot.
In both cases, this could potentially introduce even more problems than it solves, including but not limited to making it harder for her to dislodge Bastion and Torbjorn's turrets, introducing a change that proves negligible to all but two heroes who probably should be able to be killed in a single bodyshot due to the amount of potential damage they can do, and more or less introducing a precedent where characters can be tweaked due to how well the character performs for certain individuals in certain situations (which in turn would affect how useful a character is for people of all skill levels).
A simpler alternative to curb the potential rise of Widowmaker would be to look at the two Overwatch heroes who are supposed to be a hard counter to long range characters: D.Va and Winston. As it stands now, both characters are highly mobile tanks who specialize in close range damage—an ideal way to counter snipers. For instance, D.Va's MEKA can fly and get to most ledges in the game while completely negating all incoming frontal damage. Similarly, Winston can jump over most obstacles and deploy a bubble shield to prevent Widowmaker's teammates from helping her.
However, the fact that D.Va's MEKA is virtually immobile while firing its close range guns means that Widowmaker can simply run away. On top of that, her MEKA has a giant weak spot that is located directly in the middle of the MEKA, making it fairly plausible for a Widowmaker to outgun her. Similarly, even though Winston has a fairly large pool of health, his head is massive, and his weapon does poor damage at best. At close range, Widowmaker's rifle can do more than double the damage of Winston's weapon per second, and that's not even accounting for the fact that her rifle can deal headshot damage while Winston's can't.
Needless to say, tweaking how D.Va and Winston perform could curtail how effective Widowmaker can be in the future. Plus there is an added benefit of making Overwatch's Tank heroes (other than Reinhardt and Roadhog) more enticing to pick. After all, they are supposed to function as light tanks who sacrifice team utility for close range harassment, so why not make them perform as such? At the end of the day, it may not be so much a problem with Widowmaker and her ability to kill a lot of people very quickly, but rather a problem with how some of Overwatch's Tank heroes are caught in an identity crisis of sorts where they are not sturdy enough to function as frontline tanks, nor powerful enough to function as skirmishers or pushers.