Yoda should have been Obi-Wan’s Master and instructor in the ways of the Jedi. When Obi-Wan contacts Luke as a spectral force ghost he says to go to Dagobah to be trained by the Jedi Master who trained him. He doesn’t say well Luke contact Qui-Gon’s ghost he was my master he will teach you the ways of the force.
I suspect Force Ghosts can only interact with those who met them in life, which is why Obi-Wan pointed Luke in Yoda’s direction, also why waste time mentioning a long deceased Jedi Master who is irrelevant to Luke?