That's not even remotely what "incitement to violence" means.
> Causing someone to doubt and/or lose their religion is extremely damaging.
People blaspheming is not generally believed to cause religious adherents to lose faith. And even if it did, losing faith is not generally considered to be harmful either.
> It can lead to depression, anxiety, and other mental health crisis.
Citation please. I've never heard this argument before. And since you brought it up, I could just as easily say that losing religion can help cure mental issues. A classic example would be a gay person who has been brought up to believe that they're going to hell for being gay. Losing religion is probably the best thing that could happen to their mental health.
> Islam gets a lot more flak, than, say, Buddhists.
"it doesn't discriminate" doesn't mean all religions are equally blasphemed, and I can't imagine what sort of confusion would lead you to think that made any sense.
> Speech is a weapon and can be very harmful. That's one of the major reasons totalitarian governments are terrified of free speech.
Wrong type of harm. You're talking about spreading ideas that people don't like. I'm talking about the very words themselves harming the victims.