It isn't obvious because only if you have worked with it you know about the software and that's almost always on a management level in a business.
That's how I know it, and while I did use it to track business projects (software development projects), I only used it for a short time (a couple of years). Still, I used it fairly extensively during that time.
But then, my needs aren't that complex. Rather than an expensive management software package, or even a complex number crunching spreadsheet, I'm comfortable keeping mine in plain text (actually in a table in Word, though without any sorting or calculation functions).
I'll have to investigate the uses you describe here, but again, it's not a pressing need, as my (almost) text version already serves my needs nicely, but I do want to see whether I can tie my loose plotlines together so I can track which have been resolved, and in which chapters. During my revision phase, I often cull any subplots which either never panned out, or more often, just didn't rise to a substantial element in the story and simply get cut because they're just not worth the extra pages. Though I often cut entire chapters, this would allow me to identify problematic subplots before that point, though often, I never know what'll ultimately play out until I write the entire first draft.
So while it'll likely be useful, it's not a critical, pressing need.
Like REP, I only create my timeline ad-hoc, piecemeal until I finish the entire story, and then filling in the missing pieces ad hoc as I revise the story. So even then, the timeline is not a vital element, only an aid to myself and my editors so we can figure out when something happened in the story so we can tell if there are any conflicts within the story (like meeting someone after they've died, or referencing someone before the MC actually meets them). It's important to correct those issues, but they get resolved on their own in time, not through a complex and expensive piece of software.