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.