My argumentation is based on things that you are implying, these being;
Lucid dreaming, may be unsafe, even in normal circumstances
And/or We should consider every persons situation and quantify it within what we say.
I would not be uncomfortable saying to somebody, under normal circumstances, Lucid Dreaming, is harmless to the best of my knowledge. Which is the same as “Lucid Dreaming is harmless” it is just a shortened version, without additional quantification which should be assumed to be there automatically. This for me is where people taking responsibility for themselves comes in as I explained. It’s hard to be exact with language, “Do not insert metallic things into sockets” makes perfect sense and it’d be a fool who challenged it, except, following that advice blindly, now means we can’t plug anything into that socket, including plugs which are designed for that purpose.
Fundamentally, if you are talking about whether it could be harmful to become aware that you are dreaming, whilst you are dreaming. Something which as evidence in the bible suggests, we have been doing for thousands of years and in a number of cases occurs naturally. Not to say that proves it harmless, it just means that for me, without evidence that it may be harmful, it seems a bit like scaremongering to start implying that it might harm you, especially when its based on an ambiguous reference to some guy I saw saying he believed he suffered insomnia because he tried LDing, and somebody else, who couldn’t stop LDing. (Which not to imply about people, but in a number of cases such people have been trolling.) I also assume you mean LDing, otherwise “being unable to stop dreaming” is funny, since we all dream every night and short of taking certain chemicals, we can’t stop that.
Not to demean people, but if somebody has a mental problem, or anxiety disorder, etc etc, that is not normal circumstances, therefore “Lucid Dreaming is harmless” shortened version of “To the best of our knowledge Lucid Dreaming is harmless under normal circumstances” is perfectly valid still. I’m essentially challenging the degree to which we consider abnormal situations within everyday usage of language. If a specific situation came up where somebody says, “I have X disorder, could lucid dreaming harm me” my response would be speak to the relevant professional.
In answer to your assertion that if we consider this, nobody gets harmed, but if we don’t one person may get harmed. I disagree; communication at large is harmed. We become paralysed, too afraid to say “I believe this to be harmless” just in case somebody in a different situation tries it and it isn’t for them. It’s exactly the same mentality which is making it so I have to put out a “Warning wet floor” sign every time it rains, in case somebody falls over and sues me or the company I work for. People, take responsibility for yourselves and stop expecting others to do it for you. That’s a different topic though, I guess.