[karaterobot]

Well, you did say you wouldn't mind if there was a factory next to a school. My point is that most people probably wouldn't want that, because it would be dangerous at worst and disruptive at best, and it's generally considered the job of governments to prevent that kind of thing. Whether that happens in practice in specific locations is another issue completely, as is what individual citizens want to happen.

If you think that there are situations where preventing some kinds of things (say, a toxic landfill) from being constructed next to other kinds of things (say, a preschool) is desirable, and that there should be rules around that, and that most people want an elected government to make and enforce those rules, that ought to explain why the commenter you responded to said zoning is important. Even if you disagree with any of those clauses, I think you'd understand why they felt that way.