Material function - Not compiling with certain nodes

Hi all,

I´m currently testing out the Material functions and wanted to clean up my graph by introducing a couple of material functions and reuse them.

Unfortunately this is sometimes not working as expected as i´m not allowed to use certain nodes in a MF

As you can see Nodes like “PreSkinned Local Position” or PerInstanceCustomData are not compiling with the error that the shader type is not appropiate.

I understand that i´m not able to mix this up, but that should not be decided in a material function, rather where i´m using it later on or is this a misunderstanding?
The expectation would be if i use the function in the wrong place in my graph, it should fail and complain, but not in the function itself

Please somebody might help me understanding why i´m able to use it in the graph directly, but not in a function to reuse certain behavior in the right shader stage