Nah. Just Blizz Balancing™.
"Oh no, character is a little weak! Overbuff!!!!"
"Oh no, said character is way too strong now! NERF TO HELL!!!"
If you think minor D.Va changes are "nerf to hell", I don't think you've seen Hearthstone balancing. They don't nerf any cards for months until it's absolutely necessary and then they totally nuke the cards. Starving Buzzard had it's mana costed increased from 2 to 5 (think +250% ability cooldown or -60% damage) and increased the (useless) combat stats. It became worse than it's all-class counterpart Dark Cultist that doesn't even require beasts. All-class cards are the rock bottom, the "Use this card if your class has literally 0 card draw, heal, etc.".
It's like if Reinhardt had multiple hammer options but one of them only worked if you gimped your other options ("play beasts instead of any cards you want " = "deals bonus damage if you haven't used shield in X seconds") but even without using your shield it deals less damage than Mercy's melee.
Destroying one option wouldn't be too bad in itself, you still had other viable hammer options, but the bullshit excuses were the worst. "We don't change the cards for months because we care about your collection", "We don't change the broken mechanic, we just increase the cost by 2.5 because we care about the soul of the card". "Changing cards would be too confusing for new players".
I'm actually amazed how great Overwatch team is at balancing their game with frequent, small changes that are tested in PTR. I think OW has by far the best balancing team of all Blizzard games. No blatantly overpowered heroes so people buy them with real money (Samuro had 67.5% win rate in a 5v5 game) before they're nerfed to reasonable level next month à la Heroes of the Storm, none of that terrible balancing of HS and most importantly, not masking terrible decisions behind condescending "we don't want to confuse new players" PR bullshit.