Eh. There are other reasons for an exploding offer. One is that companies don't want to get into a bidding war, so they offer a tradeoff: accept a certain offer, or find someone else willing to engage in a bidding war.
If you had exactly two job opportunities, and they were willing to negotiate down ("Oh, you'll take $80K? Great. $75K is the most we can do"), you'd probably want to use an exploding offer, too.
If you had exactly two job opportunities, and they were willing to negotiate down ("Oh, you'll take $80K? Great. $75K is the most we can do"), you'd probably want to use an exploding offer, too.