When I was doing my research a year and a half ago, one thing I came across talked about how the problem was occurring in Texas/Louisiana areas, but not really in other parts. Theories of rainfall issues and other weather patterns were speculated to be the reason for that...but nothing conclusive.
So, this may be a regional issue. California, Florida, N. Carolina, all may have different results. I have seen the problems first hand on 3 friends pools with salt, no sealer. I have chlorine, same age pool (w/ in a year), the same Oklahoma Wister coping, and no noticable roughing or discoloration of the stone surface.
Lastly, for what it is worth, Platinum pools (did not build my pool, but quoted), was no longer installing salt systems when I built my pool because they had been paying to replace stone work. A friend just got a quote from Perry Pools in Houston last week, they will do salt, but he recommended against it because of the problems he sees. The builder I used, is still using and recommending salt...so pick your answer.
I don't know anything about the chemistry and comparisons to liquid bleach, but I know what I have seen. At least in the greater Houston, TX area, it seems to be a problem.