Yes startups are all about building great products that users will love. But that love should be organic and authentic, not blind belief.
I suspect that this expectation is likely because most startups are actually bullshit products. Look at all the dumbass crypto startups and now the AI startups. Its become an institution that churns out crap so you need to be able to delude yourself into believing the nonsense to keep doing it repeatedly.
I find that the expectation of "excitement" from your developers is truly absurd.