Why is only Rama praised as ‘the follower of father’s words’ / pithrua:k paripa:lakudu and not Bheeshma or Parasurama (son of Jamadagni)?

Firstly, it was never said that Rama is the ONLY one who had followed father’s words. But he is one of the first ones who has excelled and stood as an example for the way a son should respect and