Linux

At least in macos the key you're thinking of is called command, not meta. The history of the key names is that originally the space cadet keyboard had 4 modifier keys, control, meta, super, and hyper. When emacs was originally written it was aimed at this keyboard with those modifers. When using a PC keyboard emacs often mapped meta to alt and nothing for super until the windows key was introduced by Microsoft which made it a natural option for super and so the hyper key is the only one that totally died off.