Arguing against a specific idea, such as favoring voluntary associations, by bringing up slavery, which occurred during the same period when those associations were more prominent, is a goofy way to make a point. It would be analogous to arguing that the birth of the internet on January 1, 1983, was a bad thing because gay marriage was not legal at the time or because of some other unrelated thing during that time period.

You appear to be arguing against the time period as a whole rather than addressing the specific policy I support. In other words, you have constructed a straw man argument.