Small businesses are essential in providing employment for workers who might otherwise be locked out of the mainstream economy. Small firms also drive large firms to compete for workers, thus driving up wages.
Many progressives argue rights to property are arbitrary constructs of an elite and conservative legal system; that there is nothing “natural” or legitimate about them; and that, therefore, they have no special moral status.
Disagreements between libertarians and realists are a problem. But in the current interventionist-dominated environment, the disagreements don't strike me as an especially big problem — at least for now.