Practically the only remotely common desktop or server OS where it's not still a normal way to hide files, is Windows.
a few decades ago macOS, amiga and atari were rather common, which all don't follow that convention. i don't know about BeOS/haiku. but if that hides dot-files then it's because they ported a lot of unix tools for commandline use.
i could not find anything about OS/2 but i suspect that it worked like windows.
But it all makes sense, Windows is CP/M based, not Unix based.