Smoking, Singing, and The Beatles?

Now everybody says that singing harms your voice rather than helping
it, then how come Paul McCartney and John Lennon had great voices when
they smoked a heck of a lot. It's a little more evident in John's
voice that he smoked, but Paul McCartney still had a sweet, soothing
voice even after 10 years of smoking. So can smoking help your voice
or are The Beatles just lucky? :P