Super super relevant!
The appearance of cases as a way to test applicants is not random! In fact, thinking about a real-world project, picturing yourself there, is one way I get my applicants to shift thier mindsets :)
Here's a few ways in which the skills you learn (and are tested on) while casing are relevant:
Unclear/obtuse problem, non-specific objective - You will absolutely be put on projects where the question isn't quite clear. Objectives need to be formed, context needs to be understood, and teams need to align on what they're driving towards.
Lots of information, not enough time - Just like in a case, you will be thrown into a world with tons of work already done on the project before you, extensive history about the company, many datasets and opinions, etc. etc. You'll need to quickly figure out what information you want/need, how to get it, and how to use it.
Evolving + ever-ready hypothesis - Over the course of days/weeks the hypotheses will change. The objective itself might even change. You need to always know what the company's view/position is. This isn't just for elevator CEO bump-ins (never happens). It's actually for all the meetings, workshops, etc. you'll have when stakeholders ask "Why are we even doing this? Wait, what's the point? Wait, what are we meant to be doing"
These are just some (but not all) of the ways in which casing applies to real-world consulting projects :)