I'm actually partially responsible for this. I actually designed that product at LinkedIn.
There are some people who need to stay anonymous for various reasons including lawyers, M&A people, etc. The setting for how you show up in other people's who viewed your profile is controlled by the individual user. It is a privacy thing.
The messaging when upgrading used to be much more clear - you would get to see more people who viewed you as opposed to just the last few - not de-anonymize people. They seem to have made it more ambiguous since I left.
I have the "anonymous" mode enabled on Linkedin. I do this for the same reason I am using a throwaway HN account, and - if I may presume - for the same reason you didn't put full name in your HN profile:
When I'm casually browsing around I don't want to think and worry about what the reaction might be to my name popping up everywhere.