I would hope the meta of sphere-centric politics natural degredation comes to a bit of a crux in the road. You have some traditional relationships that transcend the existance of sphere-treaty obligations. I can think of a few that have existed that have yet to be truly challenged in a way that is meaningful, as ordinarily chaining is not a factor or spheres have a superiority clause. But as time goes and relationships are built, you do develop lasting partnerships. They are reflected on paper in one fashion or another. The crux of the issue is how people want to play the game.
Spheres, and spheres specifically with very limited or exclusive treaties which align with that particular sphere offer safety. Safety, in this case obviously, is both in intelligence and tiering if someone's bothered to put the appropriate level of planning into the sphere. This mitigates risk or at least attempts to. Whether we like it or not, when groups of players assemble the environment is a veritable sieve save for some rather exceptional circumstances.
Treaty partners within these spaces who have external connections run the risk of being treated as a lesser partner or junior partner for simple sake of being some kind of risk. Now, whether that's right or wrong is neither here nor there but I do feel that particularly informs the current political meta. This forces a status quo of these entities getting blinders put on them and then the power dynamic is an uneven one. For smaller alliances, or alliances that are less politically known/powerful, this can be a rather unfortunate limiter as it demands them to put their own personal politics aside and play by their bloc's rules/politics.
In my humble opinion, this robs the average alliance of exercising its sovereignty. To boot, the entire meta robs alliances of their general sense of sovereignty, so much so these powerbrokers in the Spheres are at a place of actively disregarding the sovereignty of their treaty partners. We see a rather recent and brilliant example of this with people being signed on to an NAP extension en mass without their permission. As time goes, this is just going to get more and more common of an occurrence, as these alliances that did this are actively getting away with it. There is set precedence for violating bloc-treaty and sphere member's sovereignty with impunity.
Just expect it to happen more as time goes. I, personally, just hope those of whom do have their sovereignty disregarded make moves to hold their treaty partners accountable, otherwise we've moved into a rather dangerous age of the sphere meta.
*Edit for spelling