Ashe has been dominating the DPS scene since her buffs in april 5 months ago, and widow has been dominating since the end of double shield, we all know that, but lets go over why other DPS aren’t used despite all but sym being enabled by the lack of shields.
Widow has always been a good pick if you were good with her, but she had never been “meta” until moth double sniper, where she had 8 second grapple, as well as mercy being able to enable her heavily
Hanzo outside of that meta has never been meta due to his one shot, but instead was used for his shield break and the synergy and zoning potential that dragonstrike has, with his one shot being an added bonus.
Now, one shots are almost the only way for anything to die because of how far sustain has crept in the game
when there were only 3 healers, lucio zen and mercy, lucio was the only one with AOE healing outside of ult, providing only 16 per second to an AOE, mercy providing 60 to a single target, and zen providing 30 to a single target
then ana was released, providing 70 to a single target, but requiring aim, making it much less consistent than mercy, but still valuable if you were good at the hero.
Then late 2017 comes along, and blizzard devs have the false idea that a game needs to evolve for players to remain interested, which isn’t the case, and release new mechanics for sustain, providing high AOE heals of 80 HPS + the healing from orb + the healing from coal, which can all 3 be stacked together, brig is released, providing both the same healing output as lucio, but also providing armor, which ruins the viability of any non burst DPS, and then baptiste in 2019, providing burst 60 HP per shot in an AOE, as well as 30 HPS from his shift, and a literal defensive ult level ability
A character like tracer does 240-480 damage if you have aimbot level accuracy, GM players consider having 45%+ accuracy on tracer (against GM level movement) to be good aim. Do you see a problem here?
So when tracers are doing around 140-260 damage per clip in reality, and then having to spend a full second reloading before being able to finish the job, characters being able to put out near triple digit healing per second completely disrupts their ability to get kills
on top of that, characters like tracer genji and doom are melee range characters, meaning they put WAY more risk onto themselves, by having to play in the range of any character in the game, as well as playing in the range of all CC’s and spam damage that isnt even meant for them
Snipers take on none of that risk, but yet get 100x the reward, because their kits just straight up ignore healing. It doesnt matter how bad sustain creep gets, widow ashe and hanzo will always be good because they can ignore sustain and play with virtually no risk.
Sustain creep has to be addressed if you want snipers to go away, otherwise nothing will die at all unless they’re killed by tanks or ultimates, and that isn’t how overwatch is meant to be. Risk should have reward potential, other aim types than sniping should be able to get kills, and healing shouldn’t be so damn powerful
and if orbs were meant to be spammed, explain their sniper-like charge time please. sym gets work done either by flanking or being team pocketed to w+m1. for some 
the former with the infinite tp nerf, so sym just inherently have high hero down time due to needing to wait for team pocket all the time. no shields —> no team pocket —> sym’s got nothing for hero uptime.