So what? It's been a good idea for a hundred years. That doesn't mean it's simple to engineer in practice, but nor does it mean it's a poor idea that can't be achieved.
That's holds for transmutation, too.
And it has a thousand years of history.
Nuclear fusion has been 30 years away for like 50 years now.
When Dad told me the "fusion is always been twenty years away" joke, Brezhnev was still alive then, too.
I thought it was always 20 years away, but it seems both have been common.