Is it because there are no alternative (and more mechanically demanding) healers to Medic in TF2? Is it because of nuances in his kit that Mercy doesn’t have, like variable healing rate based on recently taken damage?
Or does he have some of the same stigma as Mercy has after all?
Becausr TF2 players aren’t toxic.
I’d say it’s a combination of him being the only proper healer (and thus not “stealing” playtime from a higher-skill character) and the fact that he doesn’t have any real escape options besides a slightly higher move speed. No Rez probably helps stop people from hating him too much as well.
I don’t know anything about the TF2 medic
Because the Heavy doesn’t fly nor the Medic can easily chase after his pocket the same way Mercy can, he also cannot outheal damage like Mercy does while also damage boosting unless he is using certain Uber Charge, in TF2 there is also limited ammo and fights not only revolve around objectives but on zone denials where the resources like ammo and health packs exist, OW is for all intents and purposes not balanced.
He has a medigun that acts like Mercy’s healing stream, after fully healing his target said target gets “overheal” which is like Lucio’s sound barrier (except it expires more slowly), after he has gotten enough charge depending on the weapon he can use Uber Charge, it is basically 8 seconds of immunity for him and his target.
In OW you’re expected to die with your team and regroup for the next push.
In TF2 when you die as medic you lose uber and the game might as well be called ubercharge simulator 2007. Now imagine playing Mercy with one life and no GA against a team of full dive.
And his charge is lost on death IIRC, which makes balancing heals vs. personal safety significantly more important.
EDIT:
I’m slow 
Yep, the only way he can keep some charge is either vita saw or uber saw, the later is a high risk high reward weapon, the thing is, even if TF2 is broken in a lot of places it rewards skill more than OW will ever do.
same with ow’s community
same with every game
there are no exceptions
For me it sounds more like losing ultimate charge upon death, but the medic is one of the few classes that has an “ultimate” if we go by the OW standards.
because medic is actually difficult. if you play him like an idiot you can easily get punished and being punished as a medic in tf2 is a much bigger deal because you lose all of your uber charge if you make a bad play and your team can end up dying because of you. with mercy your mistakes are near impossible to punish because her insane mobility. only thing you can reliably get punished for is if you press e in the middle of the entire enemy team. even if you somehow manage to mess up your healing priorities and let someone die, you can just rez them unless they did something bad like jump into the middle of the enemy team. medic in tf2 required much more thought than playing mercy even if you disregard the insane differences in their mobility.
Might has something to do with him being the only healer class in game.
Couple with you can build multiple loadouts for multiple scenarios, it gives him complexity.
That being said, barely anyone plays Medic anyways.
Really? I don’t play the game but i thought i saw a cinematic of Heavy getting blown up and his pieces floating back together. What was that about?
*edit whoops I derped, see post below
That was specific to the PvE Mann vs Machine mode. He doesn’t have rez in normal PvP.
He has no mobility and little to no self healing.
Ah, yes.
Poor you, you well adjusted average Overwatch player.
There is a rez mechanic but it’s only available in a PvE gamemode, in the actual game there isn’t such thing ,only an invincibility mechanic.
Medic can rez in MvM which is basically TF2’s co-op mode, still, Medic needs to channel his healing onto the ally which means rez is not instant.
That and he also takes mechanical skill with the crusader’s crossbow (A meta weapon which is a projectile crossbow that can heal and damage enemies which gives him an option for long range healing and burst healing)
Edit : also ,taking ‘‘crit heals’’ in mind when thinking about healing priority ,losing his game-changing ‘‘ultimate’’ (ubercharge) on death ,meaning your team is punished EXTREMELY hard when you die