I would say these reasons don't line up with my observances at all.
For instance, one of mine is "this project is so big, I don't know where to start". Once I find a piece that seems like something I can get done quickly and ease me in, things tend to go a lot easier.
Another is "I have so many (different) things to do that I don't want to do any". Presumably this is not so different than the earlier one, and it's hard to get started without an obvious plan of attack that having only one or more tasks ahead of you brings with it.
Lastly, as a lifelong procrastinator, I've noticed that waiting until the last minute to do something you need to do OFTEN results in never having to do it at all. You end up doing only things that really needed to get done.
In the end, I don't really worry about it, or I hunt for tiny tasks to get my momentum going.
As for the article's "I'm not sure how doing that work will take me to the next step" I guess? Maybe? But "I'm not sure what I would do after I finish that work (what the next step is)" I don't believe has every been a factor a single time in my life.