Get Blackboard promote to variable var does not work the same as just using Get Blackboard? Why?

I’m using a Get Blackboard node to set values inside the blackboard.

I tend to promote to variable a lot of things such when using a Cast to this and that node…but when I promote to variable the return value of the Get Blackboard node, it does not produce the same effect as when I just use the return value from a Get Blackboard node?

So now I have to keep using self → get blackboard nodes where I would normally would have just used the promoted variable of the self - get blackboard nodes…

What am I doing wrong?