This is highly dependent on the role. I have been tasked with growing teams where my mandate is to hire X number of engineers at various levels. If I found X hires and then hire X + 1 shows up and was a great fit, the company would make an exception. No exploding offers necessary.

On the other hand, sometimes you are hiring to fill a specific position rather than to generally grow a team. You have two candidates you like and you can't afford to let candidate 1 sit on the offer for three weeks. People treat it like it's nefarious on the part of the company to ever have an exploding offer, but sometimes it's just not practical.