Any analysis of a problem, requires understanding WHAT problem needs solving. The issue in real world is, buisnesses and markets (as well as technology) are changing very fast, and any in-depth analysis done two years ago might not have the same outcome as if done today again. This is a fundamental realization of agile. If you have a problem domain which is not subject to change, waterfall might be the right choice. But you almost never have that. I know it is hard to accept for us devs, often with backgrounds in Math/Physics/CS etc. because the problems we were trained to tackle there are always the same, and the laws of math and physics tend to never change (or change way slower than in modern markets).

Relevant clip perfectly highlighting the problems you have during requirement analysis: https://www.youtube.com/watch?v=BKorP55Aqvg