To explain how power works...
Some entities in the multiverse are powerful, some godlike, but sometimes, going beyond your universe's border can take all of that away, or severly weaken it, with only few exceptions (example; UserUnknown and Luggo, but we don't talk about Luggo). An example of being powerful in one universe, and being just a civilian in another is Infringio, the host of SMSC.
In Infringio's special universe, he has all power. He decide what goes, and what doesn't. He exits, he doesn't have those powers anymore, he enters, he gains them back. Same could be said for those in a universe that proclaim to be a god, they exit their universe, all power is revoked.
It's a weird mechanic in the multiverse hub, but a trusty failsafe to make sure those not trusted with powers outside their universe are dealt with.