What's the point in randomly blowing up islands? Even for villains that's retarded.
Narutoverse just ain't it aside from god tiers
Not necessarily for average characters, but he could have easily done it for:
Kaido/BM:they're insane monsters destroying whatever they want, it wouldn't have been anything insane to say they destroyed a country once
Roja/Rocks: They have really bad tempers and will kill people if they get pushed too much, but again Oda preferred saying Roger destroyed an army and Rocks destroyed towns
Young Harald/Gargling:Idk as much about these two, I guess they're more into slowly killing people for the lols as opposed to large scale destruction, but imo these all just kind of speak to how Oda himself would view the characters. I highly doubt in Oda's mind you can just walk up to the redline and destroy it, the calcs and stuff is kind of irrelevant in comparison to that, just IMO.