The Centers for Disease Control and Prevention says...
With osteoarthritis, the cartilage within a joint begins to break down and the underlying bone begins to change.
Complete Orthopedics says...
Age-related wear and tear arthritis, called osteoarthritis or degenerative arthritis, is a common source of joint crepitus in advancing age.
On the other hand, the National Institutes of Health says...
Osteoarthritis happens when the cartilage and other tissues within the joint break down or have a change in their structure. This does not happen because of simple wear and tear on the joints. Instead, changes in the tissue can trigger the breakdown, which usually happens gradually over time.
Note that according to ScienceDirect...
Coarse crepitus may be caused by inflammatory or non-inflammatory arthritis. Bone-on-bone crepitus produces a higher-frequency, palpable, audible squeak. Crepitus from within a joint should be differentiated from cracking or popping sounds caused by the slipping of ligaments or tendons over bony surfaces during motion.