They're comparable in this way:
1) First, blacks were slaves and had no rights.
2) Then, they were given "separate but equal rights" for many, many, many years
3) Then, they achieved full rights.
So if you insist on applying the course of the civil rights movement for blacks to the SSM movement, you should be OK with moving from step 1 to step 2 as an incremental step, and not trying to move directly from step 1 to step 3 while skipping step 2 altogether.