But there is one: to save the precious time of valuable people. I think it's an interesting suggestion.
I, too, really like the idea, but I wonder if, in practice, it wouldn't work because companies don't introspect deeply enough to understand what makes them distinct? For instance, if what's remarkable about your company is that you have a great culture where people goof off a lot and have a lot of fun, and still manage to get a passable amount of work done, would anyone dare to self-identify that way?
Re: your example, I see it as my job to encourage them to communicate who they are loudly and proudly! There's pressure on both sides (job-seekers and employers) to check all of the boxes. It doesn't make sense to do that at all though.
The other issue is that companies may truly be trying to find the most intelligent (for whatever that word means) person as long as she or he isn't malignant- someone who will be successful in future endeavors after the one they are hiring for is finished. In that case they are just dragging a wide net and trying to get the biggest fish. This is all throw out the window, of course, when some of their screeners have ad-hoc and very personal criteria for rejection (two typos, or not being gender-inclusive, or whatever). Then the process becomes ipso facto a cultural screening process.
What's to be confused about?
They don't give a fuck - about you, or your time.
Why? Because they perceive (rightly or wrongly) that there's no business incentive for them to do so.
Either way... if they leave you dangling, or make you answer just a few silly questions too many, and/or sign up for (nearly) unlimited numbers of whiteboarding or hacker ranks sessions, or "take-home projects" they never (or at best only barely) look at, it's because... look, do you think these people have time to think about what they're doing, let alone how it affects the time and patience of those candidates they don't necessarily want to hire... or even, in some abstract sense, their long-term reputation as a company that makes at least some kind of effort to create a not entirely-unpleasant interview process?
Of course not. It's much easier to just throw shit at the wall -- or as it were, at the whiteboard -- and see what sticks.
So that's what they do.