I hate this rhetoric. They're just crafting a narrative. Painting EG's players as "less" than Fnatic wasn't done to disrespect or devalue EG but to make the audience (who definitely don't care as much as vlr.gg do about the matches) believe in an underdog. To make them believe that the players playing better than their best (even if it's not necessarily true).
It's not possible to prove the doubters wrong if there were no doubters in the first place and the casters may choose to take that position if it suits the story they want to tell.