Quote Originally Posted by Segev View Post
Thinking about the example of traveling to the plane if fire, it isn't that it lets you go where the plot is. It is that it lets you go where the fiery enemy's boss is to try to go over his head. Maybe the DM meant for you to go there; maybe not. But when you can just do it, then you can do it on your own terms and when it is use full to you.
Being able to go in the Plane of Fire and talk to your enemy's boss requires more than "on your own term", whether you can cast a spell or find a portal.

Spells like Plane Shift requires you to have a plane-attuned tuning fork, and you need to know where the boss is pretty precisely. And the boss needs to exist in the first place, of course.

The dynamic is different, between "I have a spell for that" and "there is a portal for that", but both requires just as much DM-intervention.