It was and is a perfectly good term, but people started using it without regard for its definition. I don't know why people wouldn't misuse a "better" term the same way.
In this case I think the current zeitgeist (at least among zoomers and younger millennials) really loves the word "vibe". Once they hear of the term "vibe coding", they just want to be able to say it, even if what they're doing isn't really vibe coding.
And then that leaks outside their social and age groups, because other people hear the incorrect usage, get confused, and incorporate that confusion into their own use of the term.