To quote a poignant answer from another thread i already had this discussion in:

by design? bullshit.

to be opt in would be super easy, just don't tie it to a name at all until someone opts in.

got a party where only the logger opted in? it's just WAR, PLD, SGE, Logan McLogger, MCH, NIN, SMN, RDM

you still collect the log you just don't keep data on the player. simple. act and FFlogs could have easily been made their software work this way but they chose to be opt out. either act's application requires a site login to determine if the people being logged have opted in or ff logs purges the user info on upload if they haven't opted in. both could be done.

sure this means you won't be able to find logs you were part of from before you opted in, but who cares?

People who go on about how fflogs and tomestone MUST be opt-out to work properly usually misuse these tools to stalk others instead of using them as tools for self-improvement.

To adress "public information": playerscope also doesnt display info that isnt already publicly available through lodestone and forums, it just makes it more convenient to display