Baby registry

Why don't people ever buy off the registry for baby showers?? My shower is in a few days and about 6 things were bought between both of my registries. There's stuff that is specifically not on there because I got it already, so the stuff that's on there is stuff I really need. I've heard this happen to a lot of other people too. I don't understand why people can't just go on the registry and get something instead of going to pick out something on their own 🙄