Was just learning some Hilchos Yontof in Rambam. He paskens that you are not allowed to turn off the flame even if it will smoke up your house (4,6) because since it is not necessary for cooking, it is just like any other melacha and is osur med'oraisa (4,2).
My question is that I believe I have learned elsewhere that most kibuy is a melacha sheina tzricha lgufa, since the only time you use kibuy to create something is when you are trying to make charcoal or a better wick. When you do it to get rid of the flame or smoke you are not doing anything creative. Doesn't the mishna say hamechabeh es haner mipnei goyim mipnei listim mipnei ruach raah oh bishvil hacholeh sheyishen patur.
My understanding of melacha sh'eina trzricha lgufa is that you do a melacha which is the same act, but for a different purpose than in the mishkan. Is the Rambam paskening like Rebbe Yehudah that all melacha ShETLG is asur?
BTW, melacha ShETLG is different than davar sheein miskaven which is when you do act A, but someteimes B happens simultaneously, and you have no kavanah for B. Psik Reisha is when B always happens as a result of A (and asur either because it is now my melacha or else my machshava). Psik Reisha dlo nicha lei is when you do not like when B happens (and some hold even if you do not care about B, as long as it gives you no benefit, even if you don't dislike it, it is still patur).
So my questions are A) why do you get malkos, and B) why doesn't Rambam mention Melacha ShETLG here, and C) what about mishna in Shabbos above (which I am too lazy to look up now)?



