I am definitely one of those users, or close enough that it doesn't matter. I found Reddit towards the end of college so my subs migrated quite quickly from the defaults, at the time, to smaller and smaller subs. I hadn't seen it much before, but from my few years I have seen small subs I've enjoyed turned to cesspools more often then not. As time goes one more people will jump ship to alternatives, like Hubski.
However, the biggest issue with switching to any alternative is the breath they have. Reddit having such a huge userbase allows me to find the niche subreddits that are interesting to me, but places like Hubski I find somewhat barren in that regard. It feels like the only discussion you can find are in the global feeds. Maybe that has changed though, since the last time I looked here.
All I know is I have to take a look around and see how Hubski has changed since last I looked around.