Interviewing is like flirting. Your vibe right now is "fuck dating, I'm a man, you're a woman, let's get married because we don't completely hate each other. You aren't that good looking, neither am I, but time's ticking."
Who wants to settle for that type of partner/employee, especially if that's who they are in the honeymoon phase of dating/interviewing.
Conflating finding a partner (flirting) with finding a place that will transact your time and expertise for money (job searching) says more about how you see the world than you might realize.
Not everyone flirts for the exclusive purpose of 'finding a partner', to take the analogy further. Some people do it to find someone to sleep with.
Not everyone works to 'transact your time and expertise for money' - some people want to 'fulfill a mission' with meaningful work, and build a purpose driven career.
The analogy works better than you think - at the end of the day, all I'm talking about is making a good first impression. What you may be looking for is up to you, but if you are looking to enter a mutually beneficial relationship whether it's personal, romantic, or financial - acting like a sourpuss isn't going to help you.
You are nitpicking my phrasing to fit your rhetoric device - 'finding a partner' does include finding a partner... for the night.
Of course people want a meaningful job to some extent. According to Herzberg's dual-factor theory, challenging or meaningful work is a motivator that gives positive satisfaction in the workplace. But Herzberg successfully identified that the hygiene factors such as salary (meaningful in the 'transaction' sense of a job) are much more important.
'Transacting your time and expertise for money' is one of the main drivers for working (a hygiene factor), 'fulfill a mission' is merely a motivator. We have known and taught this to managers since the 70s.
A competent employer will of course know about this - be it through having competently trained management or just experience. Managers know that some candidates are completely happy with a high hygiene + low motivation mix. In some situations, this is completely fine and not 'acting like a sourpuss' as you describe it.
Who wants to settle for that type of partner/employee, especially if that's who they are in the honeymoon phase of dating/interviewing.