Red wine was first invented in Armenia, in the Stone Age. As far as we can tell, people weren’t worried about letting their wine breathe back then.
The reason that the whole breathing thing has come up more recently is that people are worried there’s too much sulphur added in the fermentation process. The idea behind letting the wine breathe is that by giving the wine some contact with oxygen, it’ll improve the taste.
The fact is, just letting the wine sit in a bottle with the cork off for half an hour is nearly useless. It just doesn’t get enough oxygen to make a difference. But pouring wine into a decanter can make a larger difference and gain the wine a little more oxygen. Problem solved!