[Jonathan]

PokerStars is not making you pay to use tracking software.
PokerStars is trying to protect their customers from the unwanted
use of data. I don't particularly like the fact that my opponents can
go to a website that collects data about me, without my permission.

The 3 cent transfer is just PokerStars mechanism for indicating that
a player "opts in" to have his data tracked by the given tracking service.
Since most players, other than diehard Sharkscope users will probably
not bother, the default is that most players will "opt out" and that the
tracking service will then be prohibited from displaying data for that
user id.

That is their intention. It will not inhibit you from using whatever
service you like, but it will probably have the effect of making
the data less complete and less accurate over time.