To be overly simplistic you are modifying the path the susp takes so under braking the spindle tries to move down.

You will note the “B” car upper is not level to the ground already

There are a couple of ways to look at it, well probably 20, with anti dive if you force the wheel back if it will try move down.
Also with brake antidive if you twist the spindle back on the bottom, forward at the top it will rotate down.

By slanting the back of the upper control arm down this causes the upper ball joint to move forward as it goes down. As the brakes try and turn the spindle forward, it will pull down.

If you dropped the front way down but also dropped the front of the lower way down the resistance of the spindle while stopping would pull it back and down creating anti dive as well.
There are a billion interrelated factors that all get affected so it is not a matter of just tossing a wack of anti dive in.


One directly related thing is the car becomes incredibly harsh with too much.

It has been years since I have worked with changing arm angles and I am sure there will be guys here that are much more up to date than I.
Gerry

 

Doesn't it also put a lot more stress on the ball joints, control arms, bushings, frame mount points and whatnot?

I don't think these cars are all that bad for brake dive. Especially considering when all these geometries were engineered. There are a lot of cars with far more recent engineering that dive worse. My Camaro is one that comes to mind.