But if they don't know the difference and they feel they are improving who's to say they are wrong? They may not be learning how do dance in the current tradition, but they are learning their own way and perhaps it works for them - perhaps it even works better.
There's more than one way to skin a cat, as they say...
While I like your statement, I would also like to note that certainly there are people in the position for saying them being wrong - their dance partner, or whoever is dancing with them. I don't mean it as "why don't you lead? Why don't you follow?" type of arguments. But if that self learning person is hurting me, I am fairly certain that I could, and probably should tell him or her that you are wrong.
By 'they' I really did mean the dance partnership, not just the lead . ['They' is plural in original English anyway though it is certainly used now to mean 'one person who is genderless', as you may have read it]. Thus, for it to work for 'them' then it would also have to work for the partner.