Just to have concrete numbers to work with, suppose initial offers exactly correspond to final pay and that you're currently making toward the lower end of that range (e.g. because raises haven't kept up with your increased skill and increased market demand).
If you're currently making $X/yr (total comp), you think you _might_ be worth $X+$50k to somebody, and you spit out $X+$50k as your target range, a prospective employer could generously offer $X+$60k and you'd be happy as a clam and none the wiser while missing out on a new Tesla per year in extra pay.
There's a separate argument that if you'd be happy with $X+$60k then you shouldn't try to squeeze your employer for more, but I'll let somebody else make it if they'd like. Regardless, that big of a spread really does exist, and I imagine it grows further into one's career.
Specially in small/medium companies, a lot of the times businesses don’t know what they are looking for.
I know of a place that was looking for a “hardware engineer with 10y experience”. The average salary for this kind of job posting is not that high, they offered way more, but that’s because the actual position was “we’re looking for someone to become COO, and we need him to understand hardware development because the rest of the team doesn’t”.
To my layman understanding, the larger the difference between expectations, the lower the value in this tactic of not revealing your expectations.
I would imagine (perhaps unreasonably) that a relatively seasoned person on the job market would have a reasonable understanding of their market value within a few percentage points - so the recruiter might be willing to pay up to $105/hour, while you low balled it at $100/hour.