As I see it, it is missing something like: >Unlike what is common on other FSBO websites with flat fee listings, no MSL listing or co-broke fees exist. Withou

As I see it, it is missing something like: >Unlike what is common on other FSBO websites with flat fee listings, no MSL listing or co-broke fees exist. Without it, it seems that in the first part of the sentence the subject is FSBO websites, so that the implied subject of the second part of the sentence is "this site".