You try not to park on hills haha. But the concept is the same you just get better/quicker at doing it. When you’re letting off the clutch, the engine is connected to the wheels. Its enough to not need the brakes so you give it a bit more gas to get over the resistance of trying to go up a hill versus flat ground.
But some manuals will “hold” the brakes for a few seconds after you let off the brake pedal.
Also, everyone who drives manual stalls. You just laugh at how dumb you are and try again.
It’s raining out and the road your on starts going up a hill. Theres a lot of water on the road so you’re not driving fast. An automatic sees your rpms dropping because you need more power to go up the hill. It doesn’t know its raining. It downshifts to give you more power to get up the hill. You went from 50 mph at 1300rpms to 45 mph at 5000 rpms. All that power now going to your tires creates more opportunity for your wheels to loose traction in the rain and fishtail.
In a manual you put in a gear that keeps your rpms high enough to maintain speed but not 5000 rpms to “go faster”. The power to the wheels stays exactly where you want it to be based on the road conditions. Replace with snow, sleet, etc etc.