If those stages were so good for those characters (Unapproachable as you put it), then why am I never CP'd there by those characters?
I have YET to see an IC player CP someone to Frigate, or Falco to Halberd (I've seen matches like SK92 vs MoJoe on that stage, but I think it was MoJoe's pick). Like seriously, nobody picks those kind of stages for those kind of characters. 1 in part because they have better options to start with like the Neutrals, and 2 because well... those really aren't good stages for them overall.
People CP THOSE characters to THOSE stages to try and get an advantage over them. People take Falco/IC's/Diddy to Frigate because they think "Hey, I can try to knock him off the right side of the stage, or **** him when the stage needs to flip" or "Hey I can try to disrupt their normal games and get an advantage through some feature of the stage".
If stages like Frigate/Halberd/etc are GOOD for Falco/Diddy/IC's, then we should all give up on this game because Humanity will never be saved at this rate lol.