Today, the only way to choose paths inside journeys is by selecting segments.
So if I want to differentiate a path based on a tag that a subscriber has I need to create a segment with that tag and then select the segment.
The same goes for if I want to segment by product purchased. And everything else, really.
So my entire database grows out of proportion because, for every single point of data that I have and want to use, I need to create a segment.
It doesn't make sense to create a tag "Joined Product X Promotion" and then create a segment "Segment - Tagged with Product X Promotion". And then create another segment "Segment - Bought Product X" — especially if I already have that information provided via API.
So, at least, we should be able to use these elements with the journey's flow: