What companies are trying to avoid is the failure scenario with an office full of miserable people, constantly complaining about each other and finding creative new ways to slack off. That leads to burnout just as surely as 100 hour weeks do.
I just watched the Netflix documentary about the Fyre festival last night, and it seems analogous: it's actually worse to get people excited about a dream that doesn't exist than for people to be open-eyed about what something actually is.
I highly doubt that's a large number.
If employees are not responsible for their work, can't take chances and have every decision second guessed by more senior people fiercely guarding their little sphere of influence, that's when you breed such resentment.
You see this too with 'bikeshedding', there appears to be delegation taking place, but it is a farce. In this case there are too many captains on a single ship, nobody can take charge and nobody is responsible and free to give it their best and possibly fail.
The most important parts of most project work are grunt and grit, not "passion" and other such BS oriented at Disney-nurtured adults.
As for grit, nobody has ever paid me enough to deserve mine. Interest will get me to go above and beyond, otherwise I'll just perform well enough for 8h and I'm outta there. My grit is reserved for stuff that matters.
But also in the sense of grunt work.
An office full of miserable people usually indicates poor management, which no amount of passion can really offset.
I think there's a lot of pressure to "enjoy" work because good-paying work is a lot harder to find these days. Not to mention that our work is deeply ingrained in our identity (at least in the US). I get asked what I do for a living 95% of the time when I meet new people in the US, and exactly 0% when I meet new people in Europe.