>>2576333Because it's slower, less accurate, and causes you to miss opportunities more than any other mode. And when you're new, it leads to regularly fucked up exposures, like anon is posting.
You don't need to fully control your camera. That's why you pay upwards of $1000 for one that can take the burden off of you. So long as you have a firm grasp if what ISO, aperture, and shutter speed are, you can get all the control you could ever need in every priority mode, and let the camera do the needle matching for you so you can take well exposed photos, rather than saying "Oh damn I missed that because I forgot I was on 1/2 shutter speed for no reason from yesterday when I was trying to shoot the cum coming out of my dick and landing on the printed photo of chloe moretz with motion blur.