Yeah, it no doubt is. What I was trying to say is that I’m not sure whether MacOS allows characters which Obsidian doesn’t, and therefore has the same failure mode for drag-and drop.
As for the set of characters it disallows, I too feel it is because it makes it so that filenames are cross-platform, as you said.
It’s not a severe bug by any means, but, if Obsidian’s decision is to disallow those characters, drag-and-drop should not silently fail on platforms where you may encounter them.