I think if the roles were reversed and there was audio of a man saying to a woman "I hit you, I didn't punch you, don't be a baby" or if you heard evidence of a woman trying to hide in the bathroom whilst a man told her to come out and fight - you'd not have the same sense of confusion.
I think this comes from the idea that we believe women can't hurt men in the same way - because - they are physically stronger. But if you know anything about abuse, you will know that Johnny Depp's injuries are invisible because the worst part of abuse is the part you can't see.
Abuse is a pattern of control. The abuser love bombs you, gains your trust and then begins to excerpt control in escalating ways and once they are done or if you try and leave they aim to destroy you. Physical violence is a tiny part of it. Although Johnny behaved badly at times, it's obvious he did not have the hallmarks of an abuser. He did not isolate her from people, he did not push for quick commitment, he did not love bomb her, he tried to run away from altercations.
I experienced a very similar situation with a male friend who went through a very similar pattern with a woman and have seen first-hand how it begins, how it sustains and what it does to a person.
A woman appeared in his life who presented herself as kind, funny, caring and deeply interested in him. She feigned liking all the same music, activities and a special connection and he took it at face value at a lonely time in his life. She told him sob stories of her past for sympathy and ingratiated herself. Johnny Depp describes an identical experience. As does almost every person who has been abused.
Within 6 months of embarking on a relationship with this woman, my friend has been completely isolated from others and was being hit, blackmailed, gaslit, manipulated, deprived of sleep, controlled and was living his life on a weekly basis trying to do her bidding to avoid an altercation. It happened slowly, escalating each month until it was terrifying. Like Amber, she said she loved him and would die without him. He was told it was his fault and if he was just do x,y,z then she would stop and they'd be happy. Again, typical abuser.
When he left she did everything she could to ruin his career and life, just like Amber did. She similarly painted herself as the victim and made him out to be crazy - which was easy to do after she has made him mentally ill. And now, years later, he has PTSD and still struggles to be the person he was before this woman abused him.
I hope Johnny helps people to understand coercive control, intimate relationship abuse is genderless and can be very hard to identify unless you know what you're looking for. Amber Heard is not a victim, she is a perpetrator.