1. Not collect any information (in this case who read what article) at all. Obviously that company would be at a big disadvantage, having no access to a useful set of signals.
2. Collect the information and use it for their own goals.
3. Collect the information and make it freely available.
If I understand the article correctly, Quora went from strategy #2 to #3. From my perspective, this is a positive move. In case #3, users are aware of what is happening with their private information and may log out if they do not want to be tracked this way. It is way better than living in peaceful ignorance as in case #2. Also, the company cannot sell the private info, because it is publicly available.