That is certainly not true in all cases. It's possible that there's a second choice candidate, and the hiring manager wants to extend an offer to them as soon as the other candidate declines.
Probably more common is an experience I was in- we found a good candidate, he wanted to finish other interviews before making a decision and I gave him a few weeks to decide, then later I regretted giving him so much time. It meant I had to either pause the candidate search for a few weeks or potentially waste my time and candidates' time interviewing people when there may not be an opening.
Of course if you personally were on the job market and were actually desperate because your spouse said "maybe its time to be realistic" and the bills were piling up, then you don't have the luxury of playing this game.
Probably more common is an experience I was in- we found a good candidate, he wanted to finish other interviews before making a decision and I gave him a few weeks to decide, then later I regretted giving him so much time. It meant I had to either pause the candidate search for a few weeks or potentially waste my time and candidates' time interviewing people when there may not be an opening.