I'd disagree, as once you learn a bad habit it's hard to let it go...
It is not a bad habit to include files. It is a bad habit to include everything, as it is to import everything.
I think that a novice coder (sory zambani if that's not your case) should start with the language strutures before learning how to organize the correct compilation clusters (what to import and what to include), but I may be wrong here, as the learning process is very personal.