It's just that these managers often respond by relaying their OKRs to their teams and making them constantly-aware-of and responsible-for achieving them, rather than having the OKR be something private to the executive level that informs the manager's decisions, while they continue to run the team the way they would without OKRs.
I've been in the opposite situation, where there are priorities and goals that aren't communicated to me until way too late, and I ended up wasting a lot of time on stuff that didn't matter.