although I agree with these, I am going to debate against it.
A league is defined as
''a collection of people, countries, or groups that combine for mutual protection or cooperation.'' Note the word mutual. which is defined as ,a feeling or action, experienced or done by each of two or more parties towards the other or others. A league therefore is a type of mutual relationship, a kind of relationship in which both parties benefit, and non are harmed. Mutualism centers on the fact that there must be no form of competition between the parties involved. The experience gained by one party must positively reflect on the other parties in the same relationship.
The fact that you want some parties not to see the stats, might suggest that you don't trust the other party. Then if you don't trust him, why are you in a mutual relationship with him. Mutuality can't exist without trust, and for the to be trust the have to be complete disclosure of all type of information between the parties involved.
With the question of espionage, of course one might argue that the lack of such a button facilitate espionage. But Espionage is a part of MMORPG, and as we know, and have drawn from a recent debate on alts and DID( Dissociative Identity Disorder), was that people will play roles that are not immediately available to them in real life, as a form of enhanced ''imaginative reality''. So is it Plarium job to discourage such acts of enhanced imaginative reality to the form that they would create a button for that very purpose. These is a very important question, Should plarium discourage other form a personality in their game, which is heavily based on creation of alternative personality? Simply Should Plarium discourage people from playing as spies ?
The other argument which is linked to the last, is that espionage are normally carried out by alts, These is sometimes true, but not always. The are many leagues, Forums, and guild, in-game and out of the game that are centered on providing espionage, and relative intel into other groups. many such guild exist in old games like WC, WoW, Eve, and LoL, and other games, and I was a proud member of one, and is still( I am near the very top in leadership roles), and I can tell you those guilds, and league don't use alts.
MMORPG games are diverse, and espionage is part of the game, creating a buttun to stop such activity, will only results in people involved in espionage to evolve. And anyways, Marshals and captains have an ability to deal with these kind of activity, Kick the person out.