Teletypes, which might have been what people where thinking of in the 60s and early 70s, didn't have a CPU AFAIK.
The IBM 3270 on the other hand does significantly more processing on the device and dates to 1972 which would have made it well known in the late 70's computing world.
Now a 2MHz 8 bit CPU chip may not seem very powerful. But, people wrote very useful software using far less.