I had a serious crack at using Outlook for this a few years ago and I found it woefully inadequate. Outlook tasks are either todo or done. There's no way of monitoring "waiting on Alice for confirmation", "waiting for Bob's approval of the finished work". Related to this, the task list seems to only display one-dimensionally, e.g. I couldn't put together a useful list of my more important tasks that were due later this week alongside my less-important tasks due today. Also, tasks are effectively a pointer to an email. There's no way of tying together disparate emails into a single task. Lastly, I found myself wanting to really use tasks as a something like "tag annotations" - I'd be having 2 or 3 conversations about optimization in the team and want to note them all together along with a high-level view of things to do before and after.
I quite like Outlook and would love its task system to be more useful, enough so that I've thought of putting work into it to make it what I want. The fact is, though, that it doesn't really do most of what the author of the article wants, and it definitely isn't suitable as anything more than building blocks for a workflow system.