This was a comment in the world of classical music a hundred years ago, leading to the birth of dodecaphonic music as an approach to broadening the bandwidth available. In fact, what was actually happening is that everything was being played the same by a bunch of bored hacks who had become little better than human drum machines. If all you want is something in strict time which is a copy of some Received Opinion (RO) as to what the authoritative version should be, then your comment may have some validity. But as most performers here will tell you, no two performances are ever the same, because venues and audience are never the same and there's interaction with them. Just allow the words to drive the music and you'll find whatever comes out the far end reflects them, although they may be coloured by other influences in personal taste, available instrumentation and what you're listening to at the moment. But at root, because the words are different and have different semantic and emotional content, the tune will be different.
With the palette available, therefore, it should be one heck of a long time before what you mention happens. We've been singing the trad songs for several hundred years and it's not got boring yet.