imho Even action/rpg games with a decent story component (FF series, Mario & Luigi, Zelda, Ratchet & Clank) seem to sandwich it between action levels. Its often the reward for beating a dungeon boss or clearing a level.
I definitely feel that adventure games can more easily include much more in the way of story-telling than an action-focussed game can.
Pure adventure games can remain story-focussed, though, of course, not all do. Some use puzzles as an equivalent to 'beating the dungeon.' IMO puzzles need to make sense in the story & environment in order to keep the story-teller immersion quality. I felt Riven, Darkfall 1, Syberia 1 & Broken Sword 1 did a very good job with this.
Course that's not the only adventure game approach that works. Most of the Zork games & all the Monkey Island games left the 'immersive realism' approach strictly alone & were hilarious fun anyway.
Susan