They make them that steep so when the lakes dry up you can still launch. But then the trailer falls off the concrete at the bottom edge and you are really screwed. Those ramps get really slick too.
My Pontoon trailer came off the concrete last summer. That was a humbling experience. I ended up having a guy beside me who had it happen and jumped right in (literally lol) to get it back up on concrete. That was no fun at all....