But... the rules specifically mention moving through dungeons under the category of travelling.
No, they mention traveling as its own category: "As adventurers travel through a dungeon or the wilderness,..." First, most of our adventures don't even take place in a dungeon these days. And second, unless I'm mistaken, "travelling" and "journey" have specific meaning in english, and most of the activities that take place even in a dungeon is NOT travelling. It can happen for sure, when for example you "travel" back to the stairs to go back to the surface.
But, honestly, will you be calling exploring a dungeon and moving from room to room, clearing them of opponents "travelling" ? I know I would not. Merriam Webster: to go on a trip or journey
: to go to a place and especially one that is far away
"As adventurers travel through a dungeon." The provided example is literally a maze of tunnels, and the example danger is a stealthy creature. "For example, as the characters are exploring a maze of tunnels, the DM might decide that only those characters in the back rank have a chance to hear or spot a stealthy creature following the group, while characters in the front and middle ranks cannot."
Yes, you can travel through a dungeon, see the example above. And it's not happening often, at least to us, and I'm pretty sure to you as well if you are honest about it.
The very definition of travelling is restrictive, it's happening extremely infrequently in the game, and insisting that it applies to all the game just because one is afraid of one skill is complete over-reaction, especially since it is done with the aim of depriving characters of their survival instincts on the spurious pretext that, once in a while, they take note on a map.