> If hypothetically 10% of the population said A but you slice up B into specific enough buckets then A wins even if the overwhelming majority dislike A.
Yes, if you're only allowed to vote for a single option. If you're allowed to vote yes/no for each option, or rank them from best to worst, then this problem doesn't happen.
Brexit was only a policy question if you combined two different questions. “Should we stay in the EU?” and “What kind of foreign policy should we have?” People answering Yes to the first question also had plenty of diversity in how they wanted to answer the second question.