For broader classifications, there's nothing wrong about tracking tasks.
I agree in theory, but I'm trying not to advocate against standard practice in the developer community. The first link I sent states "In Phabricator, it would be better to create a Project (tag) to categorize this type of work", and the entire sentence (!) is linked to the other page, which states:
Creating new tracking tasks (tasks that "automatically" get resolved when all its dependency tasks are resolved) in Phabricator is discouraged. It is recommended to create a project instead.
So it seems that someone somewhere doesn't like tracking tasks. Neither discussion page shed any light.
The whiteboard sounds very nice. I found this ticket
from about 2 years ago, and the idea of "personal tags" or something else similar to the Bugzilla whiteboard for Phabricator was discussed very, very briefly and the ticket declined and closed.