I think the game in itself, in all of its parts, is designed to engage players in the fiction. Not to say that it's a given in all and every games and that idly playing just to push minis around is not valid or something, but it's clearly NOT the core experience the game is aiming for, which is "to create an exciting story of adventurers who confront perils". As such, if some groups need some guidance as to how to play this game without engaging in the fiction at all, they'll have to find some by themselves — and I don't think that's on the game designers, nor that this is complicated to do. After all, if no one cares about the fiction, why would they care about being denied their rests from time to time? "The screen is blinking red. You can't rest here." There, done.
I'll add that the DMGs (plural) do give us some guidance, here. There's an entire section about pacing and tension in the DMG24, with an Urgency and Rest sub-section, the central advice being "You can influence the pace and tension of your adventure by determining where and when the characters can rest", obviously. The section about random encounters also speak about creating urgency. One may find these insufficient, barebones or wishy-washy, of course. But it is there. And it's enough for many groups (the vast majority of which will organically care about the fiction anyway — they don't want the villagers to die because the villagers are their friends, sisters, mothers and fathers).