How do you deal with a big universe with established NPC experts the PCs could call in? Ultimately, the question is how much the players do it, and how the players and GM portray it.
My primary solution as stated there: the book’s creative team (in this case the players and GM) just has to make sure the lead characters have something important to do in the solution Dr. Strange brings up, and something that will require them to think creatively rather than just do what he says.
Another case where I’ve seen this is a game with the PCs having access to a large store of information when they have to check something odd. See Star Trek with a really big exploration ship - “Do we have a PhD level botanist on board?” Sure, this means that they could duck around any obscure skill roll by using their communicators... but it sometimes means having the ship’s PhD level botanist kidnapped by Klingons while collecting leaf samples.