My experience was with them being imposed by mid level tech managers who went to a conference, read half a book or had a consultant whispered in their ear.

They didn't know what a good OKR looked like, but know the one your proposed isn't what they want. Keep iterating until everyone gets fatigued and you eventually settle on a set of OKRs everyone hates. Then priorities move enough that none of it matters by the time you planned to measure.