Contrary to supremacist thinking everywhere, there is no center of the multiverse, or rather, with the planes being infinite in size wherever one stands could be called the center. There are certainly a great number of folk who consider Sigil to be the hub of all planar society, just as most Primes believe all existence revolves around their plane. In the grand scheme of things, however, no particular spot is more important than any other. No matter how influential a place may be, it’ll never be the source of the gods and all the planes, and things would continue on with or without it.