I think where
@Oofta is coming from is that the difficulty of the game itself doesn't change so much because of teleport, just the narrative does. I think that's a fair point. I mean it very well could be the opposite - that gaining teleport made the game into easy mode, but that's not really something that's typically seen, because the boring parts are generally glossed over until something important is about to happen - which is what we see with and without teleport (only difference is that something important may be different in each scenario).
I think one overlooked aspect of
@Oofta's point is that teleportation can help the PC's achieve their goals. So while it may not necessarily make their adventuring day easier, it may allow them to accomplish more of their goals in an adventuring day.
*I think we all agree it can be extremely helpful in escape scenarios, but I also think we all agree those aren't that typical in the course of play.