If people learned to communicate more effectively, could all disagreements be avoided?

I'd say effective communication can reduce many disagreements, but not all. That's largely because some conflicts stem from fundamental differences in values or priorities, which no amount of talking can fully resolve. For example, in my work as a UI designer, there are times when clients and I have different visions for a project. Even with clear communication, compromises are still necessary because our goals aren't perfectly aligned. That said, good communication does help us understand each other's perspectives better, which often leads to more respectful and productive discussions. So, while it's a powerful tool, it's not a magic solution for every conflict.