what about their timing and place in the 60s led to their role in drug culture? When i listen to the grateful dead it reminds me of things like Crosby Stills Nash & Young

Timing is everything when you're talking about the Dead. The early Grateful Dead were a typical rock & roll band from the early 60s. While they were California-based, they weren't quite surf, but more blues and traditional rock--with a bit of jazz mixed in. They were playing blues/garage rock music, but with extended soloing sessions like jazz. The beginnings of "psychedelic music."

As the 60s evolved, along comes LSD. Because they were known in San Francisco as the cool rock band, they were asked to play lots of events and block parties--including the now-famous acid tests. At this point, they had already developed their more psychedelic sound (lots of use of feedback, unusual song structures, long-free form jams). Their first few recorded albums are very psychedelic heavy. This is what helped cement them as the forerunners of the 60s drug culture.

However, in the 70s, they take a step away from the pysch sounds to make a few roots-inspired albums, which probably include the songs that remind you of Crosby, Stills & Nash.

The 70s move forward, as does their sound. They maintain that roots-inspired sound for a while, but still develop elements of the psychedelia that made them famous. By 80s-90s, they have that often replicated/mocked 'jam band' sound. They also release their only charting hit in the 80s and experience a resurgence of popularity, attracting large troves of younger fans who also, of course, happen to like drugs.