Yes, I think it's important to make the distinction between a "wear and tear" injury to the meniscus over time due to advanced arthritis vs. a traumatic single-event injury to the meniscus in an otherwise healthy (non-arthritic) knee.
As I understand the recent medical findings, Arthroscopic surgery does not work well in the presence of knee arthritis and meniscal
tears. I think the studies show surgery works not much better than physical therapy or placebo.
I suspect that your friend with arthritis and meniscus tear, would have fared just as well without the surgery.