Something Ive come to think about when it came to wondering the support balance issues. I was thinking about their strenghts and weakness then i though about how little some of those weakness actually matter. Not just for supports but for many characters in general.
lets takes everyone fav resurgent balance problem of mercy. Before rework her biggest weakness was highly team dependent the vast majority of her kit was made to be used on team mates, without them she cant heal or boost, GA or ress. Now thanks to to the rework with Valk she is capable of running away on her own free will. Her other large weakness was can only heal one person at a time, again the rework allowed her to heal the entire team.
and i suppose another weakness wuld be the distance she needs to actually heal but again valk allows her to do it from the sky or far away.
on the flip side we have ana with no mobility or self sustain not really compensated by anything unless you want to waste a vital utility skill. But then again zen is in the same boat, no mobility no self sustain. But he gets them slightly compensated by the fact the majority of his health is shields, high equal amounts of dmg at twice the fire rate with discord active, and gets to go invul and faster during ult/
supports are not the only problem Hanzo is notorious for not having any super weakness, effective both close and long range, and having greater mobility when sniper ideally should be melted if they get caught in close quarters.
where as characters like reaper has limited effective mobility, and no long range attacks to fight at range unlike some other character that are also close range but have attacks that deal enough damage at range to the point where their alt fires become their primary fire, looking at you roadhog.
I dont know if this is fool proof theory but i do feel like some of the most popular characters are also the character whose weakness dont mean much compared to other character weakness. Its proven wrong already at diamond ana sits at 6% which is a massive improvements from just a few months where she sub 1% at all ranks.
i dont know where i am going with this line of thinking but it is something ive noticed with blizzard balance philosophy, sym alone is getting her mobility weakness almost completely removed with her new TP with no new weakness to make up for it.