We like syntax errors because they mold thoughts more precisely. Going against that is also going against a lot of "productivity enhancers" - we build them because we expect to have a lot of code, and we want to reduce the kinds of errors that it may contain. That doesn't mean that we should abuse them to write as much code as we can, but it does turn out that way in practice.
So in an odd way Moore and co are right - we would be more free if we also constrained ourselves more on this point.
But the broader thought is that you can apply such constraints at any time, in tandem with what you already like. And that is more likely to produce an innovation than "just Forth".