To restate Voltaire, we do not agree with choices people make, but we would fight to the death to ensure they had the freedom to do so.
Liberalism in the old sense relies upon the idea that people have the right to make decisions for themselves, even if those decisions are poor ones. We can assert that the decisions are poor, or even be able to demonstrate this objectively, without wanting to constrain or force people to decide in the way we think best.
The problem is not that there is too much freedom, the problem is that many people choose poorly, and this can create problems for an entire society when too many people make poor decisions.
Past attempts to deal with this problem include strong social pressure to conform to established standards, but that carries its own problems.
“The question is — can a community adequately function as a sum of many private communities without strong unifying bonds to hold it together?”
There are minimum requirements for such subgroups to form a larger community. Even though there can be many things on which they disagree, there cannot be disagreement on how the subgroups interact with each other. You can’t play a game unless everyone agrees to a particular set of rules. There have to be defined principles that explain what people must agree upon, how they can disagree, and how disagreement can be handled.