Exploding offers are fine. Sudden exploding offers are terrible. If a company recruiter tells you at the beginning of the process: "Hey, this interview process takes two weeks and we expect a response 3 days after your offer letter, which would be 3-5 days after your last interview", then I don't know if I'd be thrilled, but I wouldn't call it bullshit.

Avoid like the plague any company that only tells you about the explosion as the grenade already has the pin out.